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1, -25, -49, 0, 0, 121, 0, 169, 0, 0, 0, 0, -289, 0, 0, -361, 0, 0, 0, 0, 0, 0, 529, 0, 0, 0, 625, 0, 0, 0, 0, 0, 0, 0, 0, -841, 0, 0, 0, 0, -961, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1225, 0, 0, 0, 0, 0, 1369, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1681, 0, 0, 0, 0, 0, 0, -1849, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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REFERENCES
| S. Ramanujan, The Lost Notebook and Other Unpublished Papers, Narosa Publishing House, New Delhi, 1988, p. 188
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FORMULA
| Expansion of product of f(-q) * P(q) where f(), P() are Ramanujan series.
G.f.: Sum_{k} (-1)^k * (6*k - 1)^2 * x^(k * (3*k - 1) / 2).
G.f.: (Sum_{k} (-1)^k * x^(k * (3*k - 1) / 2)) * (1 - 24 * Sum_{k>0} k * x^k / (1 -x^k)).
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EXAMPLE
| q - 25*q^25 - 49*q^49 + 121*q^121 + 169*q^169 - 289*q^289 - 361*q^361 + ...
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PROG
| (PARI) {a(n) = local(m); if(issquare(n = 24*n+1, &m), n * kronecker(12, m))}
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CROSSREFS
| Sequence in context: A038811 A028505 A154082 * A106632 A090093 A004936
Adjacent sequences: A143275 A143276 A143277 * A143279 A143280 A143281
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KEYWORD
| sign
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AUTHOR
| Michael Somos, Aug 04 2008
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