A338702 a(n) is the least k such that A060681(k) = n.

1, 2, 3, 6, 5, 10, 7, 14, 16, 18, 11, 22, 13, 26, 21, 30, 17, 34, 19, 38, 25, 42, 23, 46, 48, 50, 39, 54, 29, 58, 31, 62, 64, 66, 51, 70, 37, 74, 57, 78, 41, 82, 43, 86, 55, 90, 47, 94, 96, 98, 75, 102, 53, 106, 81, 110, 112, 114, 59, 118, 61, 122, 93, 126

Offset: 0

Author

Rémy Sigrist, Apr 24 2021

Keywords

• nonn

Examples

			The first terms of A060681 are: 0, 1, 2, 2, 4, 3, 6, 4, 6, 5, 10.
So: a(0) = 1, a(1) = 2, a(2) = 3, a(4) = 5, a(3) = 6, a(6) = 7, a(10) = 11.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A060681.

Programs

PARI

A060681(n) = if (n==1, 0, my (d=divisors(n)); d[#d]-d[#d-1])
{ u=0; a=vector(64, n, -1); for (k=1, oo, v=A060681(k); if (v<#a && a[1+v]<0, a[1+v]=k; while (a[1+u]>=0, print1 (a[u++]", "); if (u==#a, break (2))))) }

Formula

a(n) <= 2*n for any n > 0.