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 A145837 #12 Feb 16 2025 08:33:09
%S A145837 3,8,11,15,20,23,36,44,47,48,60,68,71,75,83,84,87,92,111,116,128,132,
%T A145837 143,144,156,159,164,167,168,183,192,200,204,207,215,224,228,231,236,
%U A145837 239,264,272,287,299,300,303,312,315,320,323,356,359,360,363,372,387
%N A145837 Indices of primes in A005891(n).
%C A145837 Corresponding centered pentagonal primes are listed in A145838 = {31, 181, 331, 601, 1051, 1381, 3331, ...}.
%H A145837 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CenteredPentagonalNumber.html">Centered Pentagonal Number</a>
%F A145837 A005891(a(n)) = A145838(n)
%t A145837 (Position[LinearRecurrence[{3,-3,1},{1,6,16},400], _?PrimeQ]// Flatten)-1 (* _Harvey P. Dale_, Sep 08 2018 *)
%Y A145837 Cf. A145838 = Primes in A005891. Cf. A005891 = Centered pentagonal numbers: (5n^2+5n+2)/2.
%K A145837 nonn
%O A145837 1,1
%A A145837 _Alexander Adamchuk_, Mar 21 2009
%E A145837 Extended by _R. J. Mathar_, Mar 26 2009
%E A145837 Edited by _N. J. A. Sloane_, Apr 06 2009