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A325417 a(n) is the least number not 2*a(m) or 3*a(m)+1 for any m < n. 51
1, 3, 5, 7, 8, 9, 11, 12, 13, 15, 17, 19, 20, 21, 23, 27, 29, 31, 32, 33, 35, 36, 39, 41, 43, 44, 45, 47, 48, 49, 50, 51, 53, 55, 56, 57, 59, 60, 63, 65, 67, 68, 69, 71, 73, 74, 75, 76, 77, 79, 80, 81, 83, 84, 85, 87, 89, 91, 92, 93, 95, 99, 101, 103, 104 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

In column 1 of the following guide to related sequences, disallowed terms are indicated by the variable x representing a(m) for m < n.

Disallowed    Sequence(a)  Complement(c)  Differences(a)  Differences(c)

2x, 3x+1      A325417      A325418        A325444         A325445

3x, 2x+1      A325419      A325420        A325494         A325495

2x+1, 3x+1    A077477      A325422        A325496         A325497

2x, 3x        A036668      A325424        A325498         A325499

[3x/2], 2x    A325425      A325426        A325518         A325519

[3x/2], 2x+1  A325427      A325428        A325520         A325521

[3x/2], 3x    A325429      A325430        A325522         A325523

3x, 4x        A325431      A325432        A325525         A325526

2x, 3x-1      A325462      A325463        A325526         A325527

2x, 3x-2      A325464      A325465        A325528         A325529

2x-1, 3x-1    A325440      A325441        A325530         A325531

2x-1, 3x      A325442      A325443        A325532         A325533

2x+1, 3x+1    A325539      A325540        A325541         A325542

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 2 and 4 are disallowed, so that a(2) = 3, whence the numbers 6 and 10 are disallowed, so that a(3) = 5.

MATHEMATICA

a = {1}; Do[AppendTo[a, NestWhile[# + 1 &, Last[a] + 1,

Apply[Or, Map[MemberQ[a, #] &, Select[Flatten[{#/2, (# - 1)/3}],

IntegerQ]]] &]], {150}]; a     (* A325417 *)

Complement[Range[Last[a]], a]  (* A325418 *)

(* Peter J. C. Moses, Apr 23 2019 *)

CROSSREFS

Cf. A325418, A325444.

Sequence in context: A288525 A134407 A218979 * A183868 A299542 A144724

Adjacent sequences:  A325414 A325415 A325416 * A325418 A325419 A325420

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Apr 24 2019

STATUS

approved

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Last modified January 24 19:12 EST 2021. Contains 340411 sequences. (Running on oeis4.)