A139257 Twice Mersenne primes A000668(n).

6, 14, 62, 254, 16382, 262142, 1048574, 4294967294, 4611686018427387902, 1237940039285380274899124222, 324518553658426726783156020576254, 340282366920938463463374607431768211454

Offset

1,1

Comments

Radicals of even perfect numbers. - Charles R Greathouse IV, Feb 01 2013

Links

Table of n, a(n) for n=1..12.

F. Luca and C. Pomerance, On the radical of a perfect number, New York Journal of Math., 16 (2010), 23-30.

Formula

a(n) = 2*A000668(n).

a(n) = A000918(1 + A000043(n)) = A095121(A000043(n)). - Omar E. Pol, Jun 07 2012

Mathematica

2*(2^MersennePrimeExponent[Range[15]]-1) (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 05 2020 *)

Prog

(PARI) apply(p->2*(2^p-1), select(p->ispseudoprime(2^p-1), primes(40))) \\ Charles R Greathouse IV, Feb 01 2013

Crossrefs

Cf. A000043, A000668, A000918, A060590, A095121, A100484, A139256.

Sequence in context: A059954 A252541 A333103 * A056842 A182752 A200033

Adjacent sequences: A139254 A139255 A139256 * A139258 A139259 A139260

Keyword

nonn

Author

Omar E. Pol, Apr 23 2008

Extensions

Corrected and extended by Joerg Arndt, Jun 07 2012.

Status

approved