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 A231990 #31 Jun 16 2016 23:27:54 %S A231990 5,1,2,1,5,1,2,10,4,1,4,2,4,1,8,14,8,1,8,7,11,1,6,2,14,29,2,11,9,3,2, %T A231990 11,8,13,5,4,7,6,3,24,59,9,7,1,20,5,1,8,3,33,27,11,9,12,3,2,11,9,27,4, %U A231990 2,5,12,1,5,16,54,80,37,15,1,6,3,33,3,17,5,9,17,1,35,32,2,72,10,3,82,6,4,6,5,2,1,5,31,14,13 %N A231990 First differences of Stanley sequence S(0,5) (A187843). %C A231990 For known formulas of differences of other Stanley sequences see A093682. %H A231990 Ralf Stephan, <a href="/A231990/b231990.txt">Table of n, a(n) for n = 1..999</a> %o A231990 (PARI) NAP(sv,N)=local(v,vv,m,k,l,sl,vvl);sl=length(sv);vvl=min(N*N,10^5);v=vector(N);vv=vector(vvl);for(k=1,sl,v[k]=sv[k];for(l=1,k-1,vv[2*v[k]-v[l]]=1));m=v[sl]+1;for(k=sl+1,N,while(m<=vvl&&vv[m],m=m+1);if(m>vvl,return(v));for(l=1,k-1,sl=2*m-v[l];if(sl<=vvl,vv[sl]=1));vv[m]=1;v[k]=m);v %o A231990 S05(n)=N=1000;NAP([0,5],N)[n] %o A231990 a(n)=S05(n+1)-S05(n) %Y A231990 Cf. A236269. %K A231990 nonn %O A231990 1,1 %A A231990 _Ralf Stephan_, Jan 30 2014