A158268 a(n) = coefficient of x^n in the (2^(n-1))-th iteration of x*C(x) where C(x) is the Catalan function (A000108), for n>=1.
1, 2, 20, 684, 84864, 40783952, 78562790592, 613738473236928, 19459342629747109248, 2496653806284295319455488, 1291725241770954532057108070400, 2687434858858114549619735481969223680
Offset: 1
Keywords
Programs
-
PARI
{a(n)=local(G=serreverse(x-x^2+O(x^(n+2))));for(i=2,n,G=subst(G,x,G));polcoeff(G,n)}