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 A177670 #5 Mar 02 2016 10:56:33 %S A177670 1,1,70,34650,63063000,304532310180,3216303433012890, %T A177670 65316931455144717352 %N A177670 Number of permutations of 4 copies of 1..n avoiding adjacent step pattern up, down, up, up, up, up. %Y A177670 Cf. A014608. %K A177670 nonn %O A177670 0,3 %A A177670 _R. H. Hardin_, May 10 2010