A064145 - OEIS

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A064145

a(n) = tau(n!-1) or number of divisors of n!-1.

1, 2, 2, 4, 2, 2, 4, 6, 4, 16, 2, 4, 2, 24, 4, 8, 8, 8, 4, 16, 8, 4, 4, 8, 4, 4, 16, 32, 2, 8, 2, 2, 4, 8, 4, 32, 2, 16, 4, 16, 16, 128, 16, 32, 32, 4, 16, 8, 4, 32, 32, 16, 64, 64, 32, 64, 32, 4, 8, 16, 16, 32, 16, 64, 16, 128, 4, 64, 32, 32, 8, 16, 32, 128, 8

(list; graph; refs; listen; history; text; internal format)

OFFSET

2,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 2..135

Hisanori Mishima, Factorizations of many number sequences

MATHEMATICA

Do[ Print[ DivisorSigma[0, n! - 1]], {n, 2, 40} ]

DivisorSigma[0, Range[2, 80]!-1] (* Harvey P. Dale, Aug 17 2024 *)

PROG

(PARI) { f=1; for (n=2, 100, f*=n; if (n>1, a=numdiv(f - 1), a=0); write("b064145.txt", n, " ", a) ) } \\ Harry J. Smith, Sep 09 2009

CROSSREFS