A121538 Increasing sequence: "if n appears then a*n+b doesn't", case a(1)=1, a=2, b=1.

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

Offset: 1

Author

Zak Seidov, Aug 06 2006

Keywords

• nonn

Comments

A 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 Alekseyev, Aug 07 2006

Crossrefs

Cf. A121539, A121540, A121541, A121542.

Programs

Mathematica

s={s1=1};With[{a=2,b=1},Do[If[FreeQ[s,(n-b)/a],AppendTo[s,n]],{n,s1+1,100}]];s

Formula

This is essentially A053661-1. - David W. Wilson, Aug 07 2006