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A166339 Numbers n such that Sum(n!/k!),k=0..n is prime. 0
1, 2, 2016, 3226, 8130 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

No further terms up to n=20000. The sequence a[n]=Sum(n!/k!),k=0..n is A000522.

LINKS

Table of n, a(n) for n=1..5.

FORMULA

n is an index of the sequence a[n]=Sum(n!/k!),k=0..n such that a[n] is prime.

EXAMPLE

For n=2, a[2]=5 which is a prime.

PROG

(PARI) a=1; for(n=1, 20000, a=n*a+1; if(ispseudoprime(a, 0), print("n="n)));

CROSSREFS

Cf. A000522 (corresponding sequence).

Sequence in context: A177188 A125635 A124361 * A024034 A101722 A004908

Adjacent sequences:  A166336 A166337 A166338 * A166340 A166341 A166342

KEYWORD

nonn

AUTHOR

Mike Oakes, Oct 12 2009

STATUS

approved

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Last modified May 16 10:43 EDT 2022. Contains 353700 sequences. (Running on oeis4.)