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 A215667 #12 May 25 2025 14:48:35 %S A215667 1,3,4,9,15,16,18,19,21,28,30,31,33,39,40,43,45,46,51,58,60,64,66,73, %T A215667 81,85,91,94,96,99,103,105,106,108,109,115,121,123,124,130,133,135, %U A215667 138,144,145,148,150,151,154,156,159,165,168,169,175,178,183,184,186 %N A215667 22n+1 is prime. %C A215667 First terms that are not in A125874: 19, 31, 39, 43, 46, 51, 58, 73, 85, 91 (terms with prime factor > 11). %H A215667 Zak Seidov, <a href="/A215667/b215667.txt">Table of n, a(n) for n = 1..1000</a> %F A215667 a(n) = (A141849(n) - 1)/22. %t A215667 Select[Range[200],PrimeQ[22#+1]&] (* _Harvey P. Dale_, May 25 2025 *) %o A215667 (PARI) isok(n) = isprime(22*n+1); \\ _Michel Marcus_, Oct 19 2013 %Y A215667 Cf. A141849, A125874. %K A215667 nonn %O A215667 1,2 %A A215667 _Zak Seidov_, Aug 20 2012