%I #23 Oct 23 2024 09:27:18
%S 1,3,54,1368,40365,1299078,44223732,1565864784,57079952046,
%T 2127818007315,80742077597610,3108398557803480,121107814518484872,
%U 4766365291226837508,189209375036491438800,7567095678024459993120,304603864960375133224533,12331716699093681951702810
%N G.f. satisfies A(x) = (1 + 9*x*A(x)^7)^(1/3).
%F a(n) = 9^n * binomial(7*n/3 + 1/3,n)/(7*n+1).
%o (PARI) a(n) = 9^n*binomial(7*n/3+1/3, n)/(7*n+1);
%Y Cf. A004987, A008931, A078532, A245114, A376636.
%K nonn,new
%O 0,2
%A _Seiichi Manyama_, Oct 23 2024