G.f. satisfies: A(x) = exp( Sum_{n>=1} [Sum_{k=0..3*n} binomial(3*n,k)^2 * x^k] / A(x)^n * x^n/n ).
A255839
G.f. satisfies: A(x) = exp( Sum_{n>=1} [Sum_{k=0..3*n} binomial(3*n,k)^2 * x^k] / A(x)^n * x^n/n ).
Terms
- a(0) =1a(1) =1a(2) =9a(3) =18a(4) =64a(5) =172a(6) =477a(7) =1368a(8) =3681a(9) =10485a(10) =28701a(11) =80829a(12) =225090a(13) =632160a(14) =1778553a(15) =5010948a(16) =14181849a(17) =40161357a(18) =114151716a(19) =324873027a(20) =926918784a(21) =2649218580a(22) =7585705665a(23) =21758756931a(24) =62508649059a(25) =179859399129a(26) =518234494662
External references
- oeis: A255839