|
|
A125050
|
|
a(1) = 1. If a(n) is composite, a(n+1) = 2*a(n)+1; otherwise, a(n+1) = 2*a(n).
|
|
2
|
|
|
1, 2, 4, 9, 19, 38, 77, 155, 311, 622, 1245, 2491, 4983, 9967, 19934, 39869, 79738, 159477, 318955, 637911, 1275823, 2551646, 5103293, 10206587, 20413175, 40826351, 81652702, 163305405, 326610811, 653221623, 1306443247, 2612886495
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
FORMULA
|
|
|
MAPLE
|
a := proc(n)
local c, k:
c, k := 1, 1:
while c < n do
if k > 1 and not isprime(k) then k := 2*k+1: else k := 2*k: fi:
c := c+1: od:
k: end: # Lorenzo Sauras Altuzarra, Jan 02 2023
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|