A347348 a(n) is the rank of A008619(n) in A164912.
1, 2, 3, 5, 4, 10, 8, 14, 6, 9, 7, 20, 13, 28, 11, 17, 12, 33, 18, 37, 15, 19, 16, 43, 24, 27, 22, 26, 23, 57, 31, 61, 21, 32, 25, 30, 36, 67, 29, 40, 35, 74, 41, 81, 39, 42, 45, 89, 46, 50, 34, 47, 48, 100, 49, 53, 38, 56, 52, 107, 60, 115, 51, 64, 54, 59
Offset: 1
Keywords
Links
- Jean-François Alcover, Table of n, a(n) for n = 1..1000
- Jean-François Alcover, Plot of a(1..1000)
- Index entries for sequences that are permutations of the natural numbers
Programs
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Mathematica
nmax = 120; ekg[n_] := ekg[n] = Module[{ee, k}, If[n <= 2, n, ee = Array[ekg, n - 1]; For[k = 1, True, k++, If[FreeQ[ee, k] && GCD[ekg[n - 1], k] != 1, Return[k]]]]]; b[n_] := Quotient[ekg[n] - 1, 2] + 1; bb = Array[b, nmax]; TakeWhile[Table[Position[bb, n], {n, 1, nmax}], Length[#] == 2&] // Flatten (* Jean-François Alcover, Nov 21 2021 *)
Formula
Interleave the occurrences in A164912.
Comments