A325442 - OEIS

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

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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