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 A091178 #38 Aug 02 2021 14:47:26
%S A091178 4,6,8,11,12,14,18,19,21,22,25,27,29,31,34,36,37,38,42,44,46,47,48,50,
%T A091178 53,58,59,61,63,65,67,68,70,73,74,75,78,80,82,84,85,88,90,93,95,99,
%U A091178 100,101,105,106,110,111,112,114,115,117,121,122,125,127,129,130
%N A091178 Numbers k such that k-th prime is of the form 6*m+1.
%C A091178 A002476 indexed by A000040.
%C A091178 Also k for which prime(k) == 1 (mod 3). - _Bruno Berselli_, Mar 04 2016
%C A091178 Sequence A091177 (indices of primes of the form 3*k-1) is this sequence's complement in the positive integers without {2}. - _M. F. Hasler_, Sep 02 2016
%C A091178 The asymptotic density of this sequence is 1/2 (by Dirichlet's theorem). - _Amiram Eldar_, Feb 28 2021
%H A091178 Zak Seidov, <a href="/A091178/b091178.txt">Table of n, a(n) for n = 1..1000</a>
%F A091178 a(n) = k such that A000040(k) = A002476(n).
%t A091178 Select[Range[200],IntegerQ[(Prime[#]-1)/6]&] (* _Harvey P. Dale_, Aug 25 2013 *)
%o A091178 (PARI) isok(n) = !((prime(n)-1) % 6); \\ _Michel Marcus_, Mar 04 2016
%Y A091178 Cf. A000040, A002476 (primes of the form 6*m+1), A091177 (indices of primes of the form 3*k-1), A024892, A024899.
%K A091178 nonn
%O A091178 1,1
%A A091178 _Ray Chandler_, Dec 26 2003
%E A091178 Definition edited by _Zak Seidov_, Oct 09 2014