A190662 Least semiprime having prime factors that differ by 2*n!.

15, 21, 85, 265, 2761, 10129, 111001, 887161, 21047881, 210471241, 1037836969, 68018232241, 361167207241, 3312775065961, 49691625984361, 1548286451713369, 16361621692416529, 294509190463488529

Offset

1,1

Links

Table of n, a(n) for n=1..18.

Example

a(5) = 2761 because 2761 = 11 * 251 , and 251 - 11 = 240 = 2*120 = 2*5!

Mathematica

f[n_] := Block[{p=3}, While[! PrimeQ[p+2*n!], p=NextPrime[p]]; p (p + 2*n!)]; Table[f[n], {n, 60}]

Crossrefs

Cf. A190663.

Sequence in context: A083372 A119101 A342806 * A274084 A350098 A334118

Adjacent sequences: A190659 A190660 A190661 * A190663 A190664 A190665

Keyword

nonn

Author

Michel Lagneau, May 16 2011

Status

approved