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A064028 Sum of the unitary divisors of n!. 1
1, 3, 12, 36, 216, 1020, 8160, 61920, 507744, 4383392, 52600704, 624249600, 8739494400, 109190390400, 1583122968000, 25318378008000, 455730804144000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..450

FORMULA

a(n) = usigma(n!) = A034448(A000142(n)).

EXAMPLE

n=6, 6! = 720, sum of the 8 unitary ones of its 30 divisors is 1020, a(6) = 720+1+16+45+9+80+5+144 = 1020.

MATHEMATICA

usigma[1] = 1; usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); usigma/@ (Range[17]!) (* Amiram Eldar, Jun 23 2019 *)

CROSSREFS

Cf. A034448, A003444, A046656, A056657, A056171, A056172, A000203, A000142, A062569.

Sequence in context: A282022 A004661 A074430 * A326241 A110950 A102744

Adjacent sequences:  A064025 A064026 A064027 * A064029 A064030 A064031

KEYWORD

nonn

AUTHOR

Labos Elemer, Sep 11 2001

STATUS

approved

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Last modified August 24 23:01 EDT 2019. Contains 326314 sequences. (Running on oeis4.)