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A205808
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G.f.: Sum_{n=-oo..oo} q^(9*n^2 + 2*n).
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3
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1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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OFFSET
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0
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LINKS
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FORMULA
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Expansion of f(x^7, x^11) in powers of x where f(, ) is Ramanujan's general theta function. - Michael Somos, Jan 19 2017
Euler transform of a period 36 sequence. - Michael Somos, Jan 19 2017
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EXAMPLE
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G.f. = 1 + x^7 + x^11 + x^32 + x^40 + x^75 + x^87 + x^136 + x^152 + x^215 + ...
G.f. = q + q^64 + q^100 + q^289 + q^361 + q^676 + q^784 + q^1225 + q^1369 + ...
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MATHEMATICA
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a[ n_] := SeriesCoefficient[ QPochhammer[ -x^7, x^18] QPochhammer[ -x^11, x^18] QPochhammer[ x^18], {x, 0, n}]; (* Michael Somos, Jan 19 2017 *)
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PROG
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(PARI) {a(n) = issquare(9*n + 1)}; /* Michael Somos, Jan 19 2017 */
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CROSSREFS
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Characteristic function of A132355.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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