A325539 a(n) is the least number not 2*a(m)+1 or 3*a(m)+2 for any m < n.

1, 2, 4, 6, 7, 10, 11, 12, 16, 17, 18, 19, 22, 24, 26, 27, 28, 29, 30, 31, 34, 36, 40, 41, 42, 43, 44, 46, 47, 48, 51, 52, 54, 58, 60, 62, 64, 65, 66, 67, 70, 71, 72, 75, 76, 77, 78, 79, 82, 84, 88, 90, 91, 94, 96, 98, 99, 100, 101, 102, 106, 107, 108, 111

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 numbers 3 and 5 are disallowed, so that a(2) = 2, whence the number 8 is 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, (# - 2)/3}],
IntegerQ]]] &]], {200}]; a       (* A325539 *)
Complement[Range[Last[a]], a]    (* A325540 *)
(* Peter J. C. Moses, Apr 25 2019 *)

Crossrefs

Cf. A325417, A325540.

Sequence in context: A259983 A050095 A102528 * A002158 A319829 A272631

Adjacent sequences: A325536 A325537 A325538 * A325540 A325541 A325542

Keyword

nonn,easy

Author

Clark Kimberling, May 07 2019

Status

approved