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 A128327 Row 2 of table A128325. 4

%I

%S 1,1,4,20,114,712,4772,33896,253102,1975610,16054568,135413280,

%T 1182664740,10675334958,99437919664,954581258020,9433732288486,

%U 95883201181772,1001411775057322,10738668800872594,118151145186400408

%N Row 2 of table A128325.

%F G.f.: A(x) = 1 + G(G(G(G(x)))) = B(G(x)), where B(x) is the g.f. of A128326 and G(x) = x + x*G(G(x)) is the g.f. of A030266.

%o (PARI) {a(n)=local(A=1+x,B);for(i=0,n,A=1+x*A*subst(A,x,x*A+x*O(x^n))); B=A;for(i=1,2,B=subst(B,x,x*A+x*O(x^n)));polcoeff(B,n)}

%Y Cf. A030266; A128325 (table), A128326 (row 1), A128328 (row 3), A128329 (main diagonal).

%K nonn

%O 0,3

%A _Paul D. Hanna_, Mar 11 2007

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Last modified February 1 12:28 EST 2023. Contains 359993 sequences. (Running on oeis4.)