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A120603
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G.f. satisfies: 16*A(x) = 15 + 27*x + A(x)^7, starting with [1,3,21].
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2
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1, 3, 21, 399, 9135, 233709, 6400947, 183585897, 5443737390, 165536020650, 5133935821014, 161768728483362, 5164132704296202, 166660621950110526, 5428573285691233650, 178234125351736454070, 5892439158797172244515
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OFFSET
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0,2
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COMMENTS
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See comments in A120588 for conditions needed for an integer sequence to satisfy a functional equation of the form: r*A(x) = c + b*x + A(x)^n.
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LINKS
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Table of n, a(n) for n=0..16.
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FORMULA
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G.f.: A(x) = 1 + Series_Reversion((1+16*x - (1+x)^7)/27). Lagrange Inversion yields: G.f.: A(x) = Sum_{n>=0} C(7*n,n)/(6*n+1) * (15+27*x)^(6*n+1)/16^(7*n+1). - Paul D. Hanna, Jan 24 2008
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EXAMPLE
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A(x) = 1 + 3*x + 21*x^2 + 399*x^3 + 9135*x^4 + 233709*x^5 +...
A(x)^7 = 1 + 21*x + 336*x^2 + 6384*x^3 + 146160*x^4 + 3739344*x^5 +...
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PROG
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(PARI) {a(n)=local(A=1+3*x+21*x^2+x*O(x^n)); for(i=0, n, A=A+(-16*A+15+27*x+A^7)/9); polcoeff(A, n)}
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CROSSREFS
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Cf. A120588 - A120602, A120604 - A120607.
Sequence in context: A101389 A108716 A084620 * A139224 A032469 A006927
Adjacent sequences: A120600 A120601 A120602 * A120604 A120605 A120606
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna, Jun 16 2006
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STATUS
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approved
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