A117293 - OEIS

A117293

Mersenne primes written in binary.

11, 111, 11111, 1111111, 1111111111111, 11111111111111111, 1111111111111111111, 1111111111111111111111111111111, 1111111111111111111111111111111111111111111111111111111111111

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OFFSET

1,1

COMMENTS

The number of bits in a(n) is equal to A000043(n). - Omar E. Pol, Feb 22 2008

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..14

Wikipedia, Mersenne prime.

FORMULA

a(n) = A007088(A000668(n)). - Amiram Eldar, Oct 22 2024

EXAMPLE

The third Mersenne prime is 31, i.e., 11111 in binary.

MATHEMATICA

Map[(10^# - 1)/9 &, MersennePrimeExponent[Range[9]]] (* Amiram Eldar, Oct 22 2024 *)

PROG

(PARI) apply(p->fromdigits(binary(p)), select(isprime, vector(20, n, 2^prime(n)-1))) \\ Charles R Greathouse IV, Sep 14 2016

CROSSREFS

Cf. A000043, A000668, A007088.

Sequence in context: A083441 A261269 A031974 * A015468 A037842 A131293

Adjacent sequences: A117290 A117291 A117292 * A117294 A117295 A117296

KEYWORD

base,nonn

AUTHOR

Jacob Vecht, Apr 23 2006

STATUS

approved