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 A248640 #5 Oct 19 2014 15:50:58 %S A248640 0,0,0,0,1,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1,1,1,1,2,2,0,0,0,0,1,0,0,0,0, %T A248640 1,0,0,0,0,1,0,0,0,0,1,1,1,1,2,2,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1,0,0,0, %U A248640 0,1,1,1,1,2,2,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1,0,0 %N A248640 Least nonnegative sequence which does not contain a 5-term equidistant subsequence (a(n+k*d); k=0,1,2,3,4) in arithmetic progression. %C A248640 See A248625 for more information, links and examples. %o A248640 (PARI) a=[];for(n=1,190,a=concat(a,0);while(hasAP(a,5),a[#a]++));a \\ See A248625 for hasAP(). Use concat(a,1) for the "positive integer" variant. %Y A248640 Cf. A248625, A248639, A248627, A229037, A241752. %K A248640 nonn %O A248640 0,24 %A A248640 _M. F. Hasler_, Oct 10 2014