A109757 Numbers n such that (10's complement factorial of n) + 1 is semiprime.

1, 3, 6, 14, 20, 21, 26, 34, 37, 39, 40, 47, 51, 54, 61, 62, 72, 74, 77, 82, 83, 86, 113, 115, 118, 127, 139, 179

Offset

1,2

Links

Table of n, a(n) for n=1..28.

Prog

(PARI) comp(n)=10^#Str(n)-n
is(n)=bigomega(prod(k=1, n, comp(k))+1)==2 \\ Charles R Greathouse IV, Jul 10 2011

Crossrefs

Cf. A110396, A109616.

Sequence in context: A096337 A175318 A281025 * A075189 A291987 A200823

Adjacent sequences: A109754 A109755 A109756 * A109758 A109759 A109760

Keyword

nonn,base

Author

Jason Earls, Aug 12 2005

Extensions

More terms from Sean A. Irvine, Jul 10 2011

Status

approved