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3, 4, 12, 0, 15, 12, 12, 0, 24, 12, 24, 0, 15, 16, 36, 0, 24, 24, 12, 0, 48, 12, 36, 0, 27, 24, 36, 0, 24, 36, 36, 0, 48, 12, 48, 0, 24, 28, 48, 0, 51, 36, 24, 0, 72, 24, 24, 0, 24, 36, 84, 0, 48, 36
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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FORMULA
| Expansion of q^(-1) * (phi^3(q) - phi^3(-q)) / 4 in powers of q^2 where phi() is a Ramanujan theta function. - Michael Somos Mar 12 2011
A005875(2*n + 1) = 2 * a(n). - Michael Somos Mar 12 2011
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EXAMPLE
| 3 + 4*x + 12*x^2 + 15*x^4 + 12*x^5 + 12*x^6 + 24*x^8 + 12*x^9 + ...
3*q + 4*q^3 + 12*q^5 + 15*q^9 + 12*q^11 + 12*q^13 + 24*q^17 + 12*q^19 + ...
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PROG
| (PARI) {a(n) = if( n<0, 0, n = 2*n + 1; polcoeff( sum( k=1, sqrtint(n
), 2 * x^k^2, 1 + x*O(x^n))^3 / 2, n))} /* Michael Somos Mar 12 2011 */
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CROSSREFS
| Cf. A005875, A005887.
Sequence in context: A041299 A001112 A042079 * A084200 A097850 A034854
Adjacent sequences: A045823 A045824 A045825 * A045827 A045828 A045829
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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