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interprime numbers
An interprime number is a composite that is the average of two consecutive primes, i.e., it is at equal distance from previous prime and next prime.

For example, 21 is an interprime since it is the average of the two consecutive primes 19 and 23.

The smallest 3 × 3 magic square whose entries are consecutive interprime numbers is

125771311257708312577116
125770951257711012577125
125771041257713712577089

The first interprimes are 4, 6, 9, 12, 15, 18, 21, 26, 30, 34, 39, 42, 45, 50, 56, 60, 64, 69, 72, 76, 81, 86, 93, 99, 102, 105, 108, 111, 120 more terms

Interprime numbers can also be... (you may click on names or numbers and on + to get more values)

ABA 18 50 64 + 99658962 aban 12 15 18 + 99000984 abundant 12 18 30 + 49999956 Achilles 72 108 288 + 99904500 admirable 12 30 42 + 99994614 alternating 12 18 21 + 98989896 amenable 12 21 45 + 99999980 amicable 1184 10856 12285 + 88110536 apocalyptic 192 312 506 + 30000 arithmetic 15 21 30 + 9999982 astonishing 15 21762 automorphic 76 376 625 + 7109376 Bell 15 678570 betrothed 195 1050 1575 + 96751395 binomial 15 21 45 + 99906180 brilliant 15 21 473 + 98244719 c.decagonal 40051 562801 1055701 + 98545801 c.heptagonal 386 736 8926 + 96487126 c.nonagonal 7381 87571 88831 + 99426151 c.octagonal 81 225 441 + 98545329 c.pentagonal 76 1756 4731 + 99903406 c.square 5513 6613 20605 + 99870845 c.triangular 64 274 12835 + 99230734 cake 15 26 42 + 94954490 Carmichael 15841 126217 656601 + 88689601 Catalan 42 compositorial 192 1728 43545600 congruent 15 21 30 + 9999982 constructible 12 15 30 + 63160320 cube 64 1728 4096 + 91125000 Cullen 897 Cunningham 15 26 50 + 99960005 Curzon 18 21 26 + 99999965 cyclic 15 69 217 + 9999895 D-number 15 21 39 + 7042323 d-powerful 334 370 376 + 9999227 de Polignac 1207 1243 3353 + 99999419 decagonal 370 855 2835 + 99985000 deceptive 15841 24013 126217 + 91281451 deficient 15 21 26 + 9999982 dig.balanced 12 15 21 + 95583996 double fact. 15 105 3840 10395 droll 72 240 4224 + 78446592 Duffinian 21 39 50 + 9999755 eban 30 34 42 + 66064046 economical 15 21 64 + 19999858 emirpimes 15 26 39 + 99999058 equidigital 15 21 64 + 19999858 eRAP 170 10620 23408 + 99699535 esthetic 12 21 34 + 98767878 Eulerian 26 120 4293 + 16777191 evil 12 15 18 + 99999998 factorial 120 3628800 fibodiv 969 4555 9267 + 95760780 Fibonacci 21 34 144 + 24157817 Friedman 625 736 1827 + 995373 frugal 625 1215 1681 + 99865625 gapful 105 108 120 + 99999936 Gilda 660 3727761 Giuga 30 858 1722 happy 86 129 176 + 9999372 harmonic 270 2970 32760 + 71253000 Harshad 12 18 21 + 99999965 heptagonal 18 34 81 + 99593892 hex 217 7957 12871 + 99308287 hexagonal 15 45 120 + 99906180 highly composite 12 60 120 + 73513440 hoax 160 274 483 + 99999058 Hogben 21 111 381 + 99450757 house 933 2847 6409 + 95211790 hungry 144 37929 33662541 hyperperfect 21 1055833 1787917 + 38749153 iban 12 21 42 + 777740 iccanobiF 39 12815 61135 idoneal 12 15 18 + 1320 impolite 64 4096 inconsummate 195 266 381 + 999993 insolite 111 Jacobsthal 21 10923 Jordan-Polya 12 64 72 + 74649600 junction 105 111 309 + 99999348 Kaprekar 45 99 77778 + 86358636 katadrome 21 30 42 + 98765310 Lehmer 15 771 1695 + 99961681 lonely 120 1344 15705 + 47326803 Lucas 18 76 1364 33385282 lucky 15 21 69 + 9999957 Lynch-Bell 12 15 312 + 9617832 magic 15 34 111 + 91625500 magnanimous 12 21 30 + 82486825 metadrome 12 15 18 + 1345679 modest 26 39 69 + 99965853 Moran 18 21 42 + 99999965 Motzkin 21 narcissistic 370 nialpdrome 21 30 42 + 99999998 nonagonal 111 154 969 + 99866019 nude 12 15 99 + 99999936 O'Halloran 12 60 260 + 924 oban 12 15 18 + 987 octagonal 21 176 225 + 99728736 odious 21 26 42 + 99999965 palindromic 99 111 282 + 99755799 pancake 56 154 254 + 99835516 panconsummate 12 15 18 + 231 pandigital 15 21 99 + 95583996 partition 15 30 42 + 20506255 pentagonal 12 176 376 + 99874320 pernicious 12 18 21 + 9999957 Perrin 12 39 1983 + 2240877 plaindrome 12 15 18 + 77778888 Poulet 645 7957 11305 + 91453705 power 64 81 144 + 99880036 powerful 64 72 81 + 99904500 practical 12 18 30 + 9999792 prim.abundant 12 18 30 + 99994614 primeval 10136 10123469 primorial 30 2310 9699690 pronic 12 30 42 + 99950006 Proth 81 129 225 + 98828289 pseudoperfect 12 18 30 + 999960 repdigit 99 111 4444 repfigit 1537 3684 4788 repunit 15 21 111 + 99450757 Rhonda 2835 5439 5664 + 77245119 Ruth-Aaron 15 50 105 + 99876217 Saint-Exupery 60 780 1620 + 98672640 Sastry 13224 self 42 64 86 + 99999950 self-describing 4444 10163331 10193133 + 42272724 semiprime 15 21 26 + 99999843 sliding 205 254 650 + 97657274 Smith 274 483 636 + 99999058 sphenic 30 42 102 + 99999965 square 64 81 144 + 99880036 star 8437 48061 70633 + 99169741 straight-line 111 246 420 + 543210 strobogrammatic 69 111 6009 + 99611966 subfactorial 1854 133496 super Niven 12 30 50 + 99900000 super-d 69 81 105 + 9999895 superabundant 12 60 120 + 73513440 tau 12 18 56 + 99999600 taxicab 32832 402597 513000 + 98040969 tcefrep 41673714 tetrahedral 56 120 165 + 91223769 tetranacci 15 56 108 + 28074040 triangular 15 21 45 + 99906180 tribonacci 81 274 410744 53798080 trimorphic 76 99 376 + 7109376 uban 12 15 18 + 99000090 Ulam 18 26 69 + 9999283 undulating 282 363 393 + 50505050 unprimeable 324 515 532 + 9999982 untouchable 120 246 288 + 999970 upside-down 64 3197 4286 + 99973111 vampire 1827 108135 116725 + 89901900 wasteful 12 18 26 + 9999982 weird 10990 16310 21770 + 997430 Wieferich 157995 684645 18485415 Woodall 15624 1948616 10485759 Zeisel 105 15387 54205 + 56052361 Zuckerman 12 15 111 + 97223112 Zumkeller 12 30 42 + 99990 zygodrome 99 111 1100 + 99996633