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 A026389 #7 May 29 2013 12:44:17 %S A026389 1,8,49,272,1440,7428,37730,189808,948909,4724160,23453001,116207424, %T A026389 575036475,2842936320,14046869575,69378730880,342590699955, %U A026389 1691519468760,8351553940355,41235710124400,203617691311370,1005560117623204 %N A026389 a(n) = number of integer strings s(0),...,s(n) counted by array T in A026386 that have s(n)=4; also a(n) = T(2n,n-2). %C A026389 Binomial transform of A002694. - _Ross La Haye_, Mar 05 2005 %F A026389 Conjecture: (n+2)*a(n) +4*(-3*n-2)*a(n-1) +2*(24*n-19)*a(n-2) +4*(-18*n+43)*a(n-3) +35*(n-4)*a(n-4)=0. - _R. J. Mathar_, May 29 2013 %K A026389 nonn %O A026389 2,2 %A A026389 _Clark Kimberling_