A347348 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

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).

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

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

Cf. A000027, A008619, A164912.

Cf. A064664.

Sequence in context: A215526 A246841 A066417 * A254669 A227913 A079521

Adjacent sequences: A347345 A347346 A347347 * A347349 A347350 A347351

KEYWORD

nonn

AUTHOR

Paul Curtz, Nov 21 2021

STATUS

approved