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 A096571 #5 Mar 30 2012 18:57:05 %S A096571 0,0,1,1,1,2,3,6,12,20,33,59,104,181,319,557,971,1705,2985,5218,9138, %T A096571 15993,27984,48992,85749,150061,262656,459721,804597,1408263,2464815, %U A096571 4313962,7550509,13215258,23129801,40482775,70854694,124012664 %N A096571 Number of compositions of n with first part 3 and no equal adjacent parts; this is column 3 of the array in A096568. %F A096571 Define s(0)=1, T(1, 1)=1 and T(i, j)=0 for j>i. For n>=2 and 1<=k<=n, define s(n)=T(n, 1)+T(n, 2)+...+T(n, n) and T(n, k)=s(n-k)-T(n-k, k). (This is array A096568.) %Y A096571 Cf. A003242, A096568, A096569, A096570, A096572. %K A096571 nonn %O A096571 1,6 %A A096571 _Clark Kimberling_, Jun 27 2004