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A071828 Primes of the form Sum_{i=1..k} (-1)^(k-i)*i!. 9
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)).
MATHEMATICA
l = Abs@Accumulate[(-1)^#*#! & /@ Range@99]; l[[Flatten@Position[l, _?PrimeQ]]] (* Hans Rudolf Widmer, Feb 27 2023 *)
PROG
(PARI) for(n=1, 120, if(isprime(abs(sum(i=1, n, (-1)^i*i!)))==1, print1(abs(sum(i=1, n, (-1)^i*i!)), ", ")))
(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
Sequence in context: A321875 A359808 A005165 * A280067 A158615 A321652
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 June 25 17:15 EDT 2024. Contains 373706 sequences. (Running on oeis4.)