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A026184
a(n) = (1/3)*s(n), where s(n) is the n-th multiple of 3 in A026136.
3
1, 3, 5, 2, 7, 9, 11, 4, 13, 15, 17, 6, 19, 21, 23, 8, 25, 27, 29, 10, 31, 33, 35, 12, 37, 39, 41, 14, 43, 45, 47, 16, 49, 51, 53, 18, 55, 57, 59, 20, 61, 63, 65, 22, 67, 69, 71, 24, 73, 75, 77, 26, 79, 81, 83, 28, 85, 87, 89, 30, 91, 93, 95
OFFSET
1,2
LINKS
F. M. Dekking, Permutations of N generated by left-right filling algorithms, arXiv:2001.08915 [math.CO], 2020.
FORMULA
a(4*n) = 2*n, a(4*n+1) = 6*n+1, a(4*n+2) = 6*n+3, a(4*n+3) = 6*n+5 . - Philippe Deléham, Nov 02 2023
MATHEMATICA
Block[{a, r, s, nn = 141}, a[1] = 1; Do[If[! IntegerQ[a[#1]], Set[a[#1], i], Set[a[#2], i]] & @@ {i - #, i + #} &@ Floor[i/2], {i, 2 nn}]; Select[TakeWhile[Array[a[#] &, nn], IntegerQ], Mod[#, 3] == 0 &]/3] (* Michael De Vlieger, Aug 27 2021 *)
LinearRecurrence[{0, 0, 0, 2, 0, 0, 0, -1}, {1, 3, 5, 2, 7, 9, 11, 4}, 70] (* Harvey P. Dale, Sep 25 2024 *)
CROSSREFS
Sequence in context: A125132 A352849 A243352 * A026208 A120837 A208754
KEYWORD
nonn,easy
EXTENSIONS
Edited by N. J. A. Sloane, Jan 31 2020
STATUS
approved