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A097340 Expansion of (eta(q^2)^2/(eta(q)eta(q^4)))^24 in powers of q. +0
2
1, 24, 276, 2048, 11202, 49152, 184024, 614400, 1881471, 5373952, 14478180, 37122048, 91231550, 216072192, 495248952, 1102430208, 2390434947, 5061476352, 10487167336, 21301241856, 42481784514, 83300614144 (list; graph; listen)
OFFSET

-1,2

COMMENT

Euler transform of period 4 sequence [24,-24,24,0,...].

G.f. A(x) satisfies 0=f(A(x),A(x^2)) where f(u,v)= uv(u^3+v^3) +(-u^3+48u^2-96u)v^3 +(48u^3+1791u^2+2352u)v^2 +(-96u^3+2352u^2-10496u)v +4096.

REFERENCES

S. Ramanujan, Modular Equations and Approximations to pi, pp. 23-39 of Collected Papers of Srinivasa Ramanujan, Ed. G. H. Hardy et al., AMS Chelsea 2000. See page 26.

LINKS

T. D. Noe, Table of n, a(n) for n=-1..1000

FORMULA

G.f. (1/q)(Product_{k>0} (1+q^(2k-1)))^24 = 64(G_n)^24 where q=e^(-pi sqrt(n)) and G_n is Ramanujan's class invariant.

PROGRAM

(PARI) a(n)=local(A); if(n<-1, 0, n++; A=x^n*O(x); polcoeff( (eta(x^2+A)^2/eta(x+A)/eta(x^4+A))^24, n))

CROSSREFS

Cf. A007191(n)=-(-1)^n*a(n).

Sequence in context: A045854 A014809 A007191 this_sequence A001496 A055754 A035707

Adjacent sequences: A097337 A097338 A097339 this_sequence A097341 A097342 A097343

KEYWORD

nonn

AUTHOR

Michael Somos, Aug 05 2004

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Last modified July 26 13:41 EDT 2008. Contains 142293 sequences.


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