A278637 Numbers k such that Fibonacci(k) is either prime or semiprime.

3, 4, 5, 7, 8, 9, 10, 11, 13, 14, 17, 19, 22, 23, 26, 29, 31, 34, 41, 43, 47, 53, 59, 61, 71, 73, 79, 83, 89, 94, 101, 107, 109, 113, 121, 127, 131, 137, 151, 167, 173, 191, 193, 199, 227, 251, 271, 277, 293, 331, 353, 359, 397, 401, 431, 433, 449, 467, 509, 569, 571, 587, 599, 601, 613, 631, 653, 743, 991, 1091, 1223, 1373, 1487

Offset: 1

Author

Bobby Jacobs, Jan 04 2017

Keywords

• nonn

Comments

Numbers k such that 2 <= A063375(k) <= 4.

All numbers in the first 4 rows of A279021 are in this sequence (3, 5, 11, 17, 353, 431, 509, and 587).

Are all numbers of A279021 in this sequence?

Crossrefs

Cf. A000045, A001605, A063375, A072381, A136341, A279021.

Formula

A001605 U A072381.

Extensions

a(31)-a(64) from Charles R Greathouse IV, Jan 04 2017

a(65)-a(73) from Max Alekseyev, Feb 26 2023