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A048657 Number of non-unitary divisors of n!. 5
0, 0, 0, 4, 8, 22, 44, 80, 144, 254, 508, 760, 1520, 2528, 3968, 5312, 10624, 14560, 29120, 40784, 60544, 95744, 191488, 242368, 339520, 531712, 676864, 916768, 1833536, 2331776, 4663552, 5527552, 7862272, 12163072, 16420864, 19593472 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = A000005(n!) - 2^(A000720(n)).

a(n) = A048105(n!). - Michel Marcus, Jun 30 2017

EXAMPLE

n=5, 5!=120 has 16 divisors of which 8 are not unitary:{2,60,4,30,6,20,10,12} while {1,120,3,40,5,24,15,16} are the unitary ones.

MATHEMATICA

Table[Function[k, DivisorSum[k, 1 &, ! CoprimeQ[#, k/#] &]][n!], {n, 30}] (* Michael De Vlieger, Jun 29 2017 *)

CROSSREFS

Cf. A000005, A000720, A027423, A034444, A048105, A048656.

Sequence in context: A200149 A153765 A003606 * A322284 A175655 A000639

Adjacent sequences:  A048654 A048655 A048656 * A048658 A048659 A048660

KEYWORD

nonn

AUTHOR

Labos Elemer

STATUS

approved

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Last modified January 29 07:03 EST 2020. Contains 331337 sequences. (Running on oeis4.)