A116897 - OEIS

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A116897

Numbers k such that k! - k!! + 1 is prime, where k!! denotes double factorial (A001147).

4, 6, 8, 14, 18, 28, 64, 324, 778, 882 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,1`
	COMMENTS	`Next term is greater than 3000.`
	LINKS	`Table of n, a(n) for n=1..10.`
	EXAMPLE	`6! - 6!! + 1 = 673, which is prime.`
	MATHEMATICA	`Select[Range[900], PrimeQ[#!-#!!+1]&] (* Harvey P. Dale, Mar 27 2015 *)`
	CROSSREFS	`Cf. A000142, A001147, A116896.` `Sequence in context: A173180 A200077 A256137 * A293763 A246324 A280227` `Adjacent sequences: A116894 A116895 A116896 * A116898 A116899 A116900`
	KEYWORD	`hard,more,nonn`
	AUTHOR	`Giovanni Resta, Mar 04 2006`
	STATUS	`approved`

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Last modified December 2 02:40 EST 2023. Contains 367505 sequences. (Running on oeis4.)