A166339 Numbers n such that Sum(n!/k!),k=0..n is prime.

1, 2, 2016, 3226, 8130

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 * A368214 A024034 A101722

Adjacent sequences: A166336 A166337 A166338 * A166340 A166341 A166342

Keyword

nonn

Author

Mike Oakes, Oct 12 2009

Status

approved