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A347174 Sum of cubes of odd divisors of n that are <= sqrt(n). 2
1, 1, 1, 1, 1, 1, 1, 1, 28, 1, 1, 28, 1, 1, 28, 1, 1, 28, 1, 1, 28, 1, 1, 28, 126, 1, 28, 1, 1, 153, 1, 1, 28, 1, 126, 28, 1, 1, 28, 126, 1, 28, 1, 1, 153, 1, 1, 28, 344, 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

1,9

LINKS

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

FORMULA

G.f.: Sum_{k>=1} (2*k - 1)^3 * x^((2*k - 1)^2) / (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 - 1)^2)/(1 - x^(2 k - 1)), {k, 1, nmax}], {x, 0, nmax}], x] // Rest

PROG

(PARI) a(n) = sum(k=0, sqrtint(n), if ((k%2) && !(n%k), k^3)); \\ Michel Marcus, Aug 22 2021

CROSSREFS

Cf. A001158, A051000, A069288, A069289, A280375, A347162, A347173, A347175.

Sequence in context: A040785 A040784 A347162 * A174188 A176641 A040796

Adjacent sequences:  A347171 A347172 A347173 * A347175 A347176 A347177

KEYWORD

nonn

AUTHOR

Ilya Gutkovskiy, Aug 21 2021

STATUS

approved

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Last modified October 17 17:21 EDT 2021. Contains 348065 sequences. (Running on oeis4.)