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 A172103 #10 Dec 27 2022 17:52:42
%S A172103 1,2,3,4,5,5,6,7,8,9,9,10,10,11,12,12,13,14,15,15,15,16,17,17,18,18,
%T A172103 18,19,20,21,21,22,23,23,23,23,23,24,25,26,26,27,28,29,30,30,31,31,32,
%U A172103 32,32,33,34,34,34,34,34,35,36,37,37,37,37,38,39,39,40,40,40,41,41,42,42
%N A172103 Partial sums of A167020 where A167020(n)=1 iff 6*n-1 is prime.
%C A172103 Where A167020 is the characteristic sequence: A167020(n)=1 iff 6*n-1 is prime.
%t A172103 Accumulate[Table[If[PrimeQ[6 n-1],1,0],{n,100}]] (* _Harvey P. Dale_, Dec 27 2022 *)
%o A172103 (PARI) ism(n) = isprime(6*n-1); \\ A167020
%o A172103 a(n) = sum(k=1, n, ism(k)); \\ _Michel Marcus_, Feb 06 2019
%Y A172103 Cf. A007528, A167020, A172104.
%K A172103 nonn
%O A172103 1,2
%A A172103 _Juri-Stepan Gerasimov_, Jan 25 2010
%E A172103 Entries checked by _R. J. Mathar_, Apr 14 2010