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A347162 Sum of cubes of odd divisors of n that are < sqrt(n). 3
0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 28, 1, 1, 28, 1, 1, 28, 1, 1, 28, 1, 1, 28, 1, 1, 28, 1, 1, 153, 1, 1, 28, 1, 126, 28, 1, 1, 28, 126, 1, 28, 1, 1, 153, 1, 1, 28, 1, 126, 28, 1, 1, 28, 126, 344, 28, 1, 1, 153, 1, 1, 371, 1, 126, 28, 1, 1, 28, 469, 1, 28, 1, 1, 153 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,12

LINKS

Table of n, a(n) for n=1..75.

FORMULA

G.f.: Sum_{k>=1} (2*k - 1)^3 * x^(2*k*(2*k - 1)) / (1 - x^(2*k - 1)).

MATHEMATICA

Table[DivisorSum[n, #^3 &, # < Sqrt[n] && OddQ[#] &], {n, 1, 75}]

nmax = 75; CoefficientList[Series[Sum[(2 k - 1)^3 x^(2 k (2 k - 1))/(1 - x^(2 k - 1)), {k, 1, nmax}], {x, 0, nmax}], x] // Rest

PROG

(PARI) a(n) = my(r=sqrt(n)); sumdiv(n, d, if ((d%2) && (d<r), d^3)); \\ Michel Marcus, Aug 21 2021

CROSSREFS

Cf. A001158, A051000, A333805, A333807, A339354, A347161.

Sequence in context: A040786 A040785 A040784 * A347174 A174188 A176641

Adjacent sequences:  A347159 A347160 A347161 * A347163 A347164 A347165

KEYWORD

nonn

AUTHOR

Ilya Gutkovskiy, Aug 20 2021

STATUS

approved

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Last modified October 27 01:36 EDT 2021. Contains 348270 sequences. (Running on oeis4.)