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A325417
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a(n) is the least number not 2*a(m) or 3*a(m)+1 for any m < n.
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51
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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
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OFFSET
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1,2
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COMMENTS
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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
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LINKS
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Clark Kimberling, Table of n, a(n) for n = 1..10000
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EXAMPLE
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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.
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MATHEMATICA
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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 *)
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CROSSREFS
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Cf. A325418, A325444.
Sequence in context: A288525 A134407 A218979 * A183868 A299542 A144724
Adjacent sequences: A325414 A325415 A325416 * A325418 A325419 A325420
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KEYWORD
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nonn,easy
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AUTHOR
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Clark Kimberling, Apr 24 2019
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STATUS
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approved
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