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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A277634 a(n) = 2^A000668(n) - 1.

Original entry on oeis.org

7, 127, 2147483647, 170141183460469231731687303715884105727
Offset: 1

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Author

Felix Fröhlich, Oct 24 2016

Keywords

Comments

The terms of this sequence are sometimes called "Double Mersenne numbers" (cf. A263686).
Agrees with A077586 in the first four terms, but then the two sequences differ for the first time at n = 5, because prime(5) = 11 is not in A000043.
a(5) is too large to include in data section (see A276641).
a(n) = A263686(n) iff a(n) is prime, which is the case iff A000668(n) is in A103901.
Agrees with A263686 at least in the first four terms. - Omar E. Pol, Oct 24 2016

Crossrefs

Cf. A000043, A000225, A000668, A077586, A103901, A263686, A276641.

Programs

  • PARI
    forprime(p=1, 11, if(ispseudoprime(2^p-1), print1(2^(2^p-1)-1, ", ")))

Formula

a(n) = A000225(A000668(n)).
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