A320125 - OEIS

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A320125

Number of integer solutions to a^2 + b^2 + 2*c^2 + 4*d^2 = n.

14

1, 4, 6, 8, 14, 16, 20, 32, 30, 28, 40, 40, 36, 48, 48, 32, 62, 72, 42, 72, 72, 64, 100, 96, 68, 84, 120, 80, 112, 112, 48, 128, 126, 80, 108, 128, 98, 144, 180, 96, 136, 168, 160, 168, 180, 112, 144, 192, 132, 228, 126, 144, 216, 208, 200, 160, 240, 144, 280, 232

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

COMMENTS

a(n) > 0 for n >= 0.

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..10000

FORMULA

G.f.: theta_3(q)^2 * theta_3(q^2) * theta_3(q^4).

CROSSREFS

Cf. A097057, A320124, A320126, A320127, A320128.

Sequence in context: A359676 A050902 A374190 * A110974 A173180 A200077

Adjacent sequences: A320122 A320123 A320124 * A320126 A320127 A320128

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Oct 06 2018

STATUS

approved