A325419 a(n) is the least number not 2*a(m)+1 or 3*a(m) for any m < n.

1, 2, 4, 7, 8, 10, 11, 13, 14, 16, 18, 19, 20, 22, 25, 26, 28, 31, 32, 34, 35, 36, 38, 40, 43, 44, 46, 47, 49, 50, 52, 55, 56, 58, 59, 61, 62, 64, 67, 68, 70, 72, 74, 76, 79, 80, 82, 83, 85, 86, 88, 90, 91, 92, 94, 97, 98, 100, 103, 104, 106, 107, 109, 110

Offset: 1

Author

Clark Kimberling, Apr 28 2019

Keywords

• nonn
• easy

Examples

			The sequence necessarily starts with 1.  The next 2 terms are determined as follows:  because a(1) = 1, the number 3 is disallowed, so that a(2) = 2, whence the numbers 5 and 6 are disallowed, and a(3) = 4.  See A325417 for a guide to related sequences.
		

Links

• Clark Kimberling, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A325420.

Programs

Mathematica

a = {1}; Do[AppendTo[a, NestWhile[# + 1 &, Last[a] + 1, Apply[Or,
Map[MemberQ[a, #] &, Select[Flatten[{#/3, (# - 1)/2}],
IntegerQ]]] &]], {150}]; a;     (* A325419 *)
Complement[Range[Last[a]], a];  (* A325420 *)
(* Peter J. C. Moses, Apr 23 2019 *)