

A157833


Numbers k such that 1 + Sum_{j=0..k} (1)^j*(kj)! is prime.


0



2, 3, 5, 7, 15, 19, 41, 59, 61, 105, 661, 2653, 3069, 3943, 4053
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OFFSET

1,1


COMMENTS

Note that when k is even, 3 divides the sum.
The sums corresponding to terms >= 661 are only probable primes.  Klaus Brockhaus, Mar 13 2009


LINKS



EXAMPLE

a(2) = ((1)^0)(20)! + ((1)^1)(21)! + ((1)^2)(22)! + 1 = 2!  1! + 0! + 1 = 3 (prime).


CROSSREFS



KEYWORD

nonn,more


AUTHOR



EXTENSIONS



STATUS

approved



