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A055403 Number of points in N^4 of norm <= n. 2
1, 5, 20, 70, 165, 357, 688, 1154, 1867, 2907, 4272, 6070, 8357, 11307, 14998, 19470, 24809, 31211, 38928, 47816, 58201, 70361, 83962, 99648, 117519, 137521, 160270, 185528, 213615, 244649, 279370, 317006, 358809, 404823, 454838, 509486, 568493 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..36.

FORMULA

a(n) = [x^(n^2)] (1 + theta_3(x))^4/(16*(1 - x)), where theta_3() is the Jacobi theta function. - Ilya Gutkovskiy, Apr 15 2018

CROSSREFS

Sequence in context: A084850 A270169 A007327 * A291288 A160549 A089094

Adjacent sequences:  A055400 A055401 A055402 * A055404 A055405 A055406

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified August 24 22:41 EDT 2019. Contains 326314 sequences. (Running on oeis4.)