A242866 Union of 2*A019434 and the semiprimes in A000215.

6, 10, 34, 514, 131074, 4294967297, 18446744073709551617, 340282366920938463463374607431768211457, 115792089237316195423570985008687907853269984665640564039457584007913129639937

Offset

1,1

Comments

The old definition was "Semiprimes of the form 2^(2^k) + 1 or 2^(2^k) + 2 for some k >= 0", but that does not include 10. So I replaced the old definition with the old comment, which seems a better fit. Question: is the sequence defined by the old definition in the OEIS? If not it should be added. - N. J. A. Sloane, Sep 03 2023

Links

Table of n, a(n) for n=1..9.

Wilfrid Keller, Prime factors k.2^n + 1 of Fermat numbers F_m

Crossrefs

Cf. A000215, A019434, A242832.

Sequence in context: A256721 A192774 A218860 * A360519 A363576 A361321

Adjacent sequences: A242863 A242864 A242865 * A242867 A242868 A242869

Keyword

nonn

Author

Juri-Stepan Gerasimov, May 24 2014

Extensions

Definition edited by N. J. A. Sloane, Sep 02 2023

Status

approved