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A333809 G.f.: Sum_{k>=1} (-1)^(k + 1) * x^(k*(k + 1)) / (1 - x^k). 5
0, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 2, 0, 1, 1, 1, -1, 2, 0, 1, 0, 1, 0, 2, -1, 1, 2, 1, -1, 2, 0, 2, 0, 1, 0, 2, 0, 1, 0, 1, -1, 3, 0, 1, -1, 1, 1, 2, -1, 1, 0, 2, 0, 2, 0, 1, 0, 1, 0, 3, -1, 2, 0, 1, -1, 2, 2, 1, -2, 1, 0, 3, -1, 2, 0, 1, -1, 2, 0, 1, 0, 2, 0, 2, -2, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,15
COMMENTS
Number of odd divisors of n that are < sqrt(n) minus number of even divisors of n that are < sqrt(n).
LINKS
MATHEMATICA
nmax = 90; CoefficientList[Series[Sum[(-1)^(k + 1) x^(k (k + 1))/(1 - x^k), {k, 1, nmax}], {x, 0, nmax}], x] // Rest
CROSSREFS
Sequence in context: A025916 A212211 A321764 * A306440 A350723 A025905
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Apr 05 2020
STATUS
approved

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Last modified May 27 21:52 EDT 2024. Contains 372882 sequences. (Running on oeis4.)