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

1,1

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?

Links

Table of n, a(n) for n=1..73.

Formula

A001605 U A072381.

Crossrefs

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

Sequence in context: A173153 A231711 A039131 * A191979 A072225 A137689

Adjacent sequences: A278634 A278635 A278636 * A278638 A278639 A278640

Keyword

nonn

Author

Bobby Jacobs, Jan 04 2017

Extensions

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

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

Status

approved