A099051 p*2^p - 1 where p is prime.

7, 23, 159, 895, 22527, 106495, 2228223, 9961471, 192937983, 15569256447, 66571993087, 5085241278463, 90159953477631, 378231999954943, 6614661952700415, 477381560501272575, 34011184385901985791

Offset

1,1

Comments

This is the subset of Woodall numbers of prime index. The 9th largest known Woodall prime is in this sequence: 12379*2^12379-1, where 12379 is prime, as found by Wilfrid Keller in 1984. Smaller primes are when p = 2, 3, 751. These numbers can also be semiprime, as when p = 159, 163, or 211 and hard to factor as when n = 349 (108 digits). - Jonathan Vos Post, Nov 19 2004

References

Ribenboim, P. The New Book of Prime Number Records. New York: Springer-Verlag, pp. 360-361, 1996

Links

Table of n, a(n) for n=1..17.

Eric Weisstein's World of Mathematics, Woodall Numbers.

Example

If p=3, 3*2^3 - 1 = 23.
If p=11, 11*2^11 - 1 = 22527.

Mathematica

Table[ Prime[n]*2^Prime[n] - 1, {n, 17}] (* Robert G. Wilson v, Nov 16 2004 *)

Crossrefs

Similar to Woodall numbers (A003261). Cf. A002234.

Sequence in context: A080082 A158954 A056205 * A187487 A299643 A034192

Adjacent sequences: A099048 A099049 A099050 * A099052 A099053 A099054

Keyword

nonn,easy

Author

Parthasarathy Nambi, Nov 13 2004

Extensions

More terms from Robert G. Wilson v, Nov 15 2004

Status

approved