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G.f. A(x) satisfies A(x) = (1 + x*A(x) / (1+x))^4.
1

%I #9 Mar 27 2024 08:53:39

%S 1,4,18,100,611,3964,26796,186664,1330541,9657748,71138964,530417668,

%T 3995461515,30359913132,232434013174,1791205897652,13883372595753,

%U 108159238126644,846472588860134,6651825146945508,52465622957295300,415208597109815172

%N G.f. A(x) satisfies A(x) = (1 + x*A(x) / (1+x))^4.

%F a(n) = Sum_{k=0..n} (-1)^(n-k) * binomial(n-1,n-k) * binomial(4*k+4,k)/(k+1).

%o (PARI) a(n) = sum(k=0, n, (-1)^(n-k)*binomial(n-1, n-k)*binomial(4*k+4, k)/(k+1));

%Y Cf. A371517.

%K nonn

%O 0,2

%A _Seiichi Manyama_, Mar 26 2024