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Search: id:A123648
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| A123648 |
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Expansion of eta(q^4)eta(q^28)/(eta(q)eta(q^7)) in powers of q. |
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+0
2
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| 1, 1, 2, 3, 4, 6, 9, 13, 17, 24, 32, 42, 56, 73, 96, 123, 158, 201, 254, 320, 402, 504, 624, 774, 955, 1172, 1436, 1755, 2138, 2592, 3140, 3789, 4560, 5478, 6564, 7851, 9362, 11146, 13240, 15696, 18574, 21942, 25880, 30456, 35796, 42000, 49196, 57546
(list; graph; listen)
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OFFSET
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1,3
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FORMULA
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Euler transform of period 28 sequence [ 1, 1, 1, 0, 1, 1, 2, 0, 1, 1, 1, 0, 1, 2, 1, 0, 1, 1, 1, 0, 2, 1, 1, 0, 1, 1, 1, 0, ...].
G.f. A(x) satisfies 0=f(A(x), A(x^2)) where f(u, v)= u^2 -v*(1+2*(u+v)+4*u*v).
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PROGRAM
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(PARI) {a(n)=local(A); if(n<1, 0, n--; A=x*O(x^n); polcoeff( eta(x^4+A)*eta(x^28+A)/eta(x+A)/eta(x^7+A), n))}
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CROSSREFS
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Sequence in context: A056751 A137446 A097557 this_sequence A129632 A016028 A098578
Adjacent sequences: A123645 A123646 A123647 this_sequence A123649 A123650 A123651
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KEYWORD
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nonn
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AUTHOR
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Michael Somos, Oct 04 2006
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