A347306 When k appears in A347113, or -1 if k never appears.

1, 8, 11, 2, 7, 9, 20, 12, 15, 3, 28, 13, 19, 10, 16, 21, 37, 17, 51, 23, 27, 4, 53, 24, 33, 14, 29, 34, 47, 25, 101, 30, 38, 22, 43, 31, 116, 18, 44, 39, 58, 45, 63, 48, 52, 5, 99, 49, 59, 54, 68, 60, 81, 55, 64, 50, 73, 35, 136, 56, 146, 26, 65, 69, 72, 66, 159, 74, 77, 70, 153

Offset: 1

Author

N. J. A. Sloane, Sep 01 2021

Keywords

• nonn

Comments

It is conjectured that every positive number appears in A347113. - N. J. A. Sloane, Nov 08 2021

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000 (first 3330 terms from N. J. A. Sloane)
• Hugo Pfoertner, Table of n, a(n) for n = 1..132708
• Hugo Pfoertner, Illustration of terms corresponding to first 400000 terms of A347113, use zoom to see details.

Crossrefs

Cf. A347113.

Programs

Mathematica

With[{s = Import["https://oeis.org/A347113/b347113.txt", "Data"][[All, -1]]}, Array[FirstPosition[s, #][[1]] &, 71]] (* Michael De Vlieger, Sep 01 2021 *)

Python

from math import gcd
def A347306(n):
    if n == 1:
        return 1
    i, j, nset, m = 1, 2, {1}, 2
    while True:
        k = m
        i += 1
        while k == j or gcd(k,j) == 1 or k in nset:
            k += 1
        if k == n:
            return i
        j = k+1
        nset.add(k)
        while m in nset:
            m += 1 # Chai Wah Wu, Sep 02 2021