A071828 - OEIS

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A071828

Primes of the form Sum_{i=1..k} (-1)^(k-i)*i!.

5, 19, 101, 619, 4421, 35899, 3301819, 1226280710981, 115578717622022981, 32656499591185747972776747396512425885838364422981 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,1`
	LINKS	`Charles R Greathouse IV, Table of n, a(n) for n = 1..14` `M. Zivkovic, The number of primes sum_(i=1..n)(-1)^(n-i)i! is finite, Math. Comp. vol 68 (1999) pp 403-409.`
	FORMULA	`a(n) = A005165(A001272(n)).`
	PROG	`(PARI) for(n=1, 120, if(isprime(abs(sum(i=1, n, (-1)^ii!)))==1, print1(abs(sum(i=1, n, (-1)^ii!)), ", ")))` `(PARI) v=[]; for(n=1, 1000, if(ispseudoprime(t=abs(sum(i=1, n, (-1)^i*i!))), v=concat(v, t))); v \\ Charles R Greathouse IV, Feb 14 2011`
	CROSSREFS	`Cf. A001272, A005165.` `Sequence in context: A162292 A321875 A005165 * A280067 A158615 A321652` `Adjacent sequences: A071825 A071826 A071827 * A071829 A071830 A071831`
	KEYWORD	`nonn,fini`
	AUTHOR	`Benoit Cloitre, Jun 08 2002`
	EXTENSIONS	`Edited by R. J. Mathar, Aug 28 2007`
	STATUS	`approved`

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Last modified April 6 15:23 EDT 2020. Contains 333276 sequences. (Running on oeis4.)