A325442 a(n) is the least number not 2*a(m)-1 or 3*a(m) for any m < n.

1, 2, 4, 5, 8, 10, 11, 13, 14, 16, 17, 18, 20, 22, 23, 26, 28, 29, 32, 34, 36, 37, 38, 40, 41, 44, 46, 47, 49, 50, 52, 53, 56, 58, 59, 61, 62, 64, 65, 68, 70, 72, 74, 76, 77, 80, 82, 83, 85, 86, 88, 89, 90, 92, 94, 95, 98, 100, 101, 104, 106, 107, 109, 110

Offset

1,2

Links

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

Example

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 3 and 6 are disallowed, and a(3) = 4.  See A325417 for a guide to related sequences.

Mathematica

a = {1}; Do[AppendTo[a, NestWhile[# + 1 &, Last[a] + 1, Apply[Or,
Map[MemberQ[a, #] &, Select[Flatten[{(#+1)/2, #/3}],
IntegerQ]]] &]], {150}]; a          (* A325442 *)
Complement[Range[Last[a]], a]       (* A325443 *)
(* Peter J. C. Moses, Apr 25 2019 *)

Crossrefs

Cf. A325417, A325443.

Sequence in context: A079537 A094591 A189093 * A134191 A286803 A026138

Adjacent sequences: A325439 A325440 A325441 * A325443 A325444 A325445

Keyword

nonn,easy

Author

Clark Kimberling, May 02 2019

Status

approved