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A347348
a(n) is the rank of A008619(n) in A164912.
1
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
1,2
COMMENTS
This is a permutation of the positive integers.
1, 2, 6, 9, 15, 19, ... are in a(n) and A064664(n).
FORMULA
Interleave the occurrences in A164912.
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 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul Curtz, Nov 21 2021
STATUS
approved