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Search: id:A123647
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| A123647 |
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Expansion of (eta(q^4)eta(q^12)/(eta(q)eta(q^3)))^2 in powers of q. |
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+0
2
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| 1, 2, 5, 12, 22, 42, 80, 136, 233, 396, 636, 1020, 1622, 2496, 3822, 5808, 8642, 12786, 18788, 27208, 39184, 56088, 79432, 111912, 156823, 217964, 301517, 415104, 567758, 773244, 1048616, 1414432, 1900524, 2543940, 3389792, 4501164, 5956430
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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Euler transform of period 12 sequence [ 2, 2, 4, 0, 2, 4, 2, 0, 4, 2, 2, 0, ...].
G.f. A(x) satisfies 0=f(A(x), A(x^2)) where f(u, v)= u^2 -v*(1+4*(u+v)+16*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^12+A)/eta(x+A)/eta(x^3+A))^2, n))}
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CROSSREFS
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Sequence in context: A116718 A026035 A086734 this_sequence A116711 A109653 A115520
Adjacent sequences: A123644 A123645 A123646 this_sequence A123648 A123649 A123650
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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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