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A171455 G.f. stisfies: A(x) = 1 + 2*x*AGM(1,A(x)^4). 0
1, 2, 8, 48, 336, 2560, 20608, 172432, 1484704, 13069296, 117080576, 1063944416, 9783594304, 90869069872, 851218195008, 8032861976544, 76295247548480, 728766670652368, 6996258626856320, 67467783946608064, 653254749175955584 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..20.

EXAMPLE

G.f.: A(x) = 1 + 2*x + 8*x^2 + 48*x^3 + 336*x^4 + 2560*x^5 +...

A(x)^2 = 1 + 4*x + 20*x^2 + 128*x^3 + 928*x^4 + 7232*x^5 +...

A(x)^4 = 1 + 8*x + 56*x^2 + 416*x^3 + 3280*x^4 + 27008*x^5 +...

AGM(1,A(x)^4) = 1 + 4*x + 24*x^2 + 168*x^3 + 1280*x^4 + 10304*x^5 +...

PROG

(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(i=1, n, A=1+2*x*agm(1, A^4)); polcoeff(A, n)}

CROSSREFS

Cf. A171454.

Sequence in context: A177066 A228568 A007170 * A136722 A085615 A054726

Adjacent sequences:  A171452 A171453 A171454 * A171456 A171457 A171458

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Dec 09 2009

STATUS

approved

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Last modified October 22 06:02 EDT 2018. Contains 316432 sequences. (Running on oeis4.)