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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A219548 Smallest prime factor of 2^A219547(n) + 1.

Original entry on oeis.org

257, 65537, 641, 257, 193, 257, 274177, 65537, 257, 641, 257, 449, 59649589127497217, 257, 257, 641, 65537, 257, 769, 257, 65537, 641, 257, 193, 257, 1238926361552897, 5441, 257, 257, 65537, 274177, 257, 193, 257, 641, 65537, 257, 59649589127497217, 257, 65537, 641, 257, 257, 274177, 65537, 257, 641, 257, 5953
Offset: 1

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Author

Jonathan Sondow, Nov 24 2012

Keywords

Comments

2p divides sigma_k(2p), where p = a(n) and k = A219547(n). But 2p is not the least m > 1 that divides sigma_k(m).

Crossrefs

Cf. A002586, A219547.

Formula

a(n) = A002586(A219547(n)).
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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