A152102 Numbers of the form (2^p - 1)(2^q + 1) where p and q are twin primes.

231, 3999, 16771071, 68719083519, 1152921502996234239, 19342813113827469725532159, 1329227995784915871174424803370074111, 22300745198530623141528634722924057038159871, 25711008708143844408671393477450995736753878524115705145589759

Offset

1,1

Comments

Idea resulted from seqfan posts by Artur Jasinski.

Links

Table of n, a(n) for n=1..9.

Mathematica

a[n_] := If[PrimeQ[(2*n - 1)] && PrimeQ[(2*n + 1)], (2^(2*n - 1) - 1)*(2^(2*n + 1) + 1), {}]; Flatten[Table[a[n], {n, 1, 100}]]
(2^#[[1]]-1)(2^#[[2]]+1)&/@Select[Partition[Prime[Range[100]], 2, 1], #[[2]]- #[[1]]==2&] (* Harvey P. Dale, Dec 03 2012 *)

Prog

(PARI) forprime(p=2, 1e3, if(isprime(q=p+2), print1((2^p-1)*(2^q+1)", "))) \\ Charles R Greathouse IV, Nov 07 2011

Crossrefs

Sequence in context: A260302 A211717 A029569 * A183663 A362429 A201957

Adjacent sequences: A152099 A152100 A152101 * A152103 A152104 A152105

Keyword

nonn,easy

Author

Roger L. Bagula, Nov 24 2008

Extensions

a(9) added by Harvey P. Dale, Dec 03 2012

Status

approved