id:A064147 - OEIS Search Results

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

+0
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3, 8, 10, 13, 17, 20, 22, 24, 26, 34, 39, 53, 59, 61, 63, 69, 70, 76, 80, 87, 97, 99 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`The list is complete to 102. 200 and 392 are also to be included.`
	LINKS	`Paul Leyland, Generalized Cullen and Woodall numbers` `Andrew Walker, N!+/-1 Factoring Page`
	PROGRAM	`(PARI) {A064147(n)=if(numdiv(n!-1)==numdiv(n!+1), n, 0)}`
	CROSSREFS	`Cf. A000005.` `Sequence in context: A007284 A080892 A074186 this_sequence A122529 A137920 A126581` `Adjacent sequences: A064144 A064145 A064146 this_sequence A064148 A064149 A064150`
	KEYWORD	`nonn`
	AUTHOR	`Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 11 2001`
	EXTENSIONS	`More terms from Randall L. Rathbun, Jan 11 2002`

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Last modified December 7 23:50 EST 2009. Contains 170430 sequences.