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 A061922 #3 May 01 2014 02:47:11 %S A061922 1,1,2,5,14,42,132,421,1382,4478,15580,54114,181676,650484,2289320, %T A061922 8028901,28045302,103229014,372640460,1336511110,4882492452, %U A061922 17534836812,63692926552,234287550818,868236370364,3281589811404 %N A061922 Xcatalans - produced as a self-convolved sequence like Catalan numbers (A000108) but use carryless GF(2)[ X ] polynomial multiplication. %C A061922 Shifts one place left when Xmult-convolved (XMULTCONV) with itself. %p A061922 Xcatalans(30); Xcatalans := proc(upto_n) local a,i,k; a := [1]; for i from 1 to upto_n do a := [ op(a), add(Xmult(a[k],a[i-k+1]), k=1..i)]; od; RETURN(a); end; %p A061922 XMULTCONV := proc(a,b) local c,i,k,n; n := min( nops(a), nops(b) ); c := []; for i from 0 to n-1 do c := [ op(c), add(Xmult(a[k+1],b[i-k+1]), k=0..i)]; od; RETURN(c); end; %Y A061922 For Xmult, see A048720 (Xmult table) or A048631 (Xfactorials). Other self-convolved sequences: A000108, A007460 - A007464, A025192. %K A061922 nonn,easy,eigen %O A061922 0,3 %A A061922 _Antti Karttunen_, May 15 2001