cp's OEIS Frontend

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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A182296 Prime Riesel numbers: primes p such that p*2^k - 1 is composite for all positive integers k.

Original entry on oeis.org

509203, 1330207, 2251349, 2554843, 2924861, 3177553, 3292241, 3580901, 3661529, 3661543, 4384979, 6055001, 7576559, 7629217, 8086751, 8643209, 9053711, 9203917, 9545351, 10219379, 10645867, 10913233, 10913681, 11694013, 11942443, 13161283, 14608183, 15627133
Offset: 1

Views

Author

Arkadiusz Wesolowski, Apr 23 2012

Keywords

Comments

Primes in A101036.

Examples

			509203 is the first known prime p for which p*2^k - 1 is composite for all positive integers k, so a(1) = 509203.
		

Crossrefs

A128979 Least exponent k such that p_n*(2^k) - 1 is prime.

Original entry on oeis.org

1, 1, 2, 1, 2, 3, 2, 1, 4, 4, 1, 1, 2, 7, 4, 2, 12, 3, 5, 2, 7, 1, 2, 4, 1, 10, 3, 10, 9, 8, 25, 2, 2, 1, 4, 5, 1, 3, 4, 2, 8, 3, 226, 3, 2, 1, 1, 3, 2, 1, 4, 4, 11, 6, 4, 2, 8, 1, 5, 2, 11, 2, 1, 26, 3, 6, 1, 1, 18, 3, 4, 4, 1, 7, 1, 2, 20, 5, 10, 3, 4, 7, 2, 3, 1, 6, 112, 9, 10, 7, 2, 12, 5, 46, 1, 2, 8
Offset: 1

Views

Author

Pierre CAMI and Robert G. Wilson v, Feb 16 2007

Keywords

Comments

Supposedly the difference from A101050 is that the k here are required to be strictly positive (nonzero positive). - R. J. Mathar, Dec 13 2008

Crossrefs

Programs

  • Mathematica
    f[n_] := Block[{k = 1, p = Prime@n}, While[ !PrimeQ[p*2^k - 1], k++ ]; k]; Array[f, 97]
Showing 1-2 of 2 results.