This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A121882 #18 Feb 25 2022 10:42:41 %S A121882 1,3,5,6,8,9,10,11,13,14,15,21,23,25,28,30,31,34,35,36,38,45,49,50,53, %T A121882 60,63,64,66,69,71,74,76,79,80,81,83,90,91,99,101,105,106,108,110,113, %U A121882 114,124,128,130,134,135,136,140,141,143,144,150,151,159,161,163,165 %N A121882 Numbers k such that k + D(k) + 1 is prime, where D() are the doublets, A020338. %H A121882 Robert Israel, <a href="/A121882/b121882.txt">Table of n, a(n) for n = 1..10000</a> %e A121882 9 is a term because 9 + 99 + 1 = 109 is prime. %p A121882 filter:= n -> isprime(1+n*(2+10^(1+ilog10(n)))): %p A121882 select(filter, [$1..1000]);# _Robert Israel_, Feb 23 2022 %o A121882 (PARI) isok(k) = isprime(k + eval(Str(k, k)) + 1); \\ _Michel Marcus_, Feb 25 2022 %Y A121882 Cf. A020338. %K A121882 base,easy,nonn %O A121882 1,2 %A A121882 _Jason Earls_, Aug 31 2006