A377513 - OEIS

A377513

a(n) = number of iterations of x -> 2 x - 5 to reach a nonprime, starting with prime(n+3).

1, 8, 1, 7, 1, 2, 6, 1, 1, 1, 1, 3, 5, 2, 1, 1, 3, 1, 1, 1, 2, 1, 4, 1, 1, 1, 1, 1, 4, 2, 1, 2, 1, 1, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 2, 1, 2, 1, 1, 1, 3, 2, 1, 1, 1, 7, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 2, 1, 2, 1, 1, 1, 4, 1, 1, 2, 1, 1, 1, 1

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

See A377120 for a guide to related sequences.

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

prime(5) = 11 -> 17 -> 29 -> 53 -> 101 -> 197 -> 389 -> 773 -> 1541 = 23*67, so a(2) = 8.

MAPLE

f:= proc(p) local x, i;

x:= p;