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 A163638 #7 Mar 19 2018 04:07:22 %S A163638 0,1,0,1,4,4,6,6,8,9,10,8,12,9,14,15,16,10,18,12,20,21,22,14,24,25,26, %T A163638 27,28,15,30,16,32,33,34,35,36,18,38,39,40,20,42,21,44,45,46,22,48,49, %U A163638 50,51,52,24,54,55,56,57,58,25,60,26,62,63,64,65,66,27,68,69,70,28,72,30,74,75 %N A163638 Two copies of the sequence A141468, one at prime the other at nonprime indices. %C A163638 The indices of this sequence are labeled as 0=N, 1=N, 2=P, 3=P, 4=N, 5=P, 6=N, etc. N=nonprime or P=prime. The numbers 0,1,4,6,8, etc. of A141468 are filled in once at consecutive positions marked N, and a second time at the positions marked P. %Y A163638 Cf. A000040, A001477, A141468. %K A163638 nonn,less %O A163638 0,5 %A A163638 _Juri-Stepan Gerasimov_, Aug 02 2009 %E A163638 Entries checked by _R. J. Mathar_, Aug 06 2009