

A064147


Numbers n such that n!  1 and n! + 1 have the same number of divisors, i.e., tau(n!  1) = tau(n! + 1).


1



3, 8, 10, 13, 17, 20, 22, 24, 26, 34, 39, 53, 59, 61, 63, 69, 70, 76, 80, 87, 97, 99, 103, 124, 130
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OFFSET

1,1


COMMENTS

The list is complete to 102. 200 and 392 are also to be included.
236 and 634 are terms.  Chai Wah Wu, Jan 03 2020


LINKS

Table of n, a(n) for n=1..25.
Paul Leyland, Generalized Cullen and Woodall numbers
Andrew Walker, N!+/1 Factoring Page


PROG

(PARI) {A064147(n)=if(numdiv(n!1)==numdiv(n!+1), n, 0)}


CROSSREFS

Cf. A000005.
Sequence in context: A226641 A212966 A074186 * A287573 A122529 A137920
Adjacent sequences: A064144 A064145 A064146 * A064148 A064149 A064150


KEYWORD

nonn


AUTHOR

Vladeta Jovovic, Sep 11 2001


EXTENSIONS

More terms from Randall L. Rathbun, Jan 11 2002
a(23)a(25) from Chai Wah Wu, Jan 03 2020


STATUS

approved



