A366648 Numbers k such that 4^k + 1 is a semiprime.

3, 6, 10, 14, 16, 20, 32, 46, 52, 64, 74, 128, 178, 298, 346, 502, 614, 634, 1912, 60394, 92116

Offset

1,1

Links

Table of n, a(n) for n=1..21.

Formula

The even terms of A092559 divided by 2. - Max Alekseyev, Jan 04 2024

Example

14 is in this sequence because 4^14+1 = 17*15790321 is a semiprime.

Crossrefs

Cf. A062394, A001358, A004062, A092559.

Sequence in context: A134535 A078060 A310057 * A022764 A310058 A310059

Adjacent sequences: A366645 A366646 A366647 * A366649 A366650 A366651

Keyword

nonn,more

Author

Sean A. Irvine, Oct 16 2023

Extensions

a(19)-a(21) from Max Alekseyev, Jan 04 2024

Status

approved