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A327766 Number of compositions (ordered partitions) of n into divisors of n that are at most sqrt(n). 0
1, 1, 1, 1, 5, 1, 13, 1, 34, 19, 89, 1, 927, 1, 610, 189, 4930, 1, 35890, 1, 46754, 1873, 28657, 1, 3919944, 571, 196418, 18560, 4205249, 1, 110187694, 1, 39882198, 183916, 9227465, 9496, 14484956252, 1, 63245986, 1822473, 11969319436, 1, 141930520462, 1, 34020543362, 339200673 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Table of n, a(n) for n=0..45.

FORMULA

a(n) = [x^n] 1 / (1 - Sum_{d|n, d <= sqrt(n)} x^d).

a(p) = 1, where p is prime.

MATHEMATICA

a[n_] := SeriesCoefficient[1/(1 - Sum[Boole[d <= Sqrt[n]] x^d, {d, Divisors[n]}]), {x, 0, n}]; Table[a[n], {n, 0, 45}]

CROSSREFS

Cf. A100346, A294137, A294138, A327642.

Sequence in context: A286254 A322664 A286457 * A147348 A081224 A104793

Adjacent sequences:  A327763 A327764 A327765 * A327767 A327768 A327769

KEYWORD

nonn

AUTHOR

Ilya Gutkovskiy, Sep 24 2019

STATUS

approved

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Last modified May 16 11:54 EDT 2021. Contains 343942 sequences. (Running on oeis4.)