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A138915 G.f. A(x) satisfies: 6*A(x) = A(A(A(A(A(x))))) + 5*x + x^2 with A(0)=0. 3
1, 1, 20, 1070, 82620, 7950630, 893138136, 113042205894, 15776443441194, 2393774318253534, 391021817774684352, 68276246115093735882, 12675272091572931300360, 2491402163326687657447940 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

A(A(A(A(A(x))))) is the 5th self-composition of the g.f. A(x).

LINKS

Table of n, a(n) for n=1..14.

EXAMPLE

G.f.: A(x) = x + x^2 + 20*x^3 + 1070*x^4 + 82620*x^5 +...

A(A(x)) = x + 2*x^2 + 42*x^3 + 2241*x^4 + 172960*x^5 +...

A(A(A(x))) = x + 3*x^2 + 66*x^3 + 3519*x^4 + 271550*x^5 +...

A(A(A(A(x)))) = x + 4*x^2 + 92*x^3 + 4910*x^4 + 378944*x^5 +...

A(A(A(A(A(x))))) = x + 5*x^2 + 120*x^3 + 6420*x^4 + 495720*x^5 +...

so that 6*A(x) = A(A(A(A(A(x))))) + 5*x + x^2.

PROG

(PARI) {a(n)=local(A=x+x^2, G); if(n<1, 0, for(i=3, n+1, G=x; for(j=1, 5, G=subst(A, x, G+x*O(x^i))); A=A+polcoeff(G, i)*x^i); polcoeff(A, n))}

CROSSREFS

Cf. A138739, A138913, A138914, A138916.

Sequence in context: A128482 A128476 A160132 * A006427 A072962 A224125

Adjacent sequences:  A138912 A138913 A138914 * A138916 A138917 A138918

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Apr 03 2008

STATUS

approved

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Last modified September 30 01:45 EDT 2022. Contains 357092 sequences. (Running on oeis4.)