Sequence: "if n appears then a*n+b doesn't"

[Max A.]

On 8/6/06, zak seidov <zakseidov at yahoo.com> wrote:

> %S A121538 1,2,4,6,7,8,10,11,12,14,16,18,19,20,22,24,26,27,28,30,31,32,34,35,36,38,40,42,43,44,46,47,48,50,51,52,54,56,58,59,60,62,64,66,67,68,70,72,74,75,76,78,79,80,82,83,84,86,88,90,91,92,94,96,98,99,100
>
> %N A121538 Increasing sequence: "if n appears then
> a*n+b doesn't", case a(1)=1, a=2, b=1.

Alternative description:
Positive integer n is in A121538 iff any of the following is true:
1) n is even
2) n+1 = 2^k where k is odd
3) n+1 = 2^k*(2*t+1) where t>0 and k is even

Max