A105214 Companion sequence to A103683: a(n) = k if A103683(k) = n; a(n) = 0 if n is not in {A103683}.

1, 2, 3, 6, 4, 46, 5, 10, 7, 22, 8, 50, 9, 14, 11, 18, 12, 54, 13, 26, 21, 30, 15, 58, 16, 34, 17, 42, 19, 62, 20, 38, 25, 70, 31, 66, 23, 74, 29, 78, 24, 102982, 27, 86, 41, 82, 28, 102974, 35, 98, 33, 90, 32, 102978, 36, 102, 37, 106, 39, 102990, 40, 94, 71

Offset: 1

Author

Leroy Quet and Robert G. Wilson v, Apr 13 2005

Keywords

• nonn

Comments

A103683 is injective.

Inverse of A103683.

Conjecture: a(42 + 6*k) = 0. This would follow from the conjecture that for n >= 67, A103683(n) is divisible by 3 iff n == 3 mod 4 and by 2 iff n == 2 mod 4. - Robert Israel, May 12 2015

The conjecture is false; a(42) = 102982. - Rémy Sigrist, Jan 05 2022

Examples

			a(6) = 46 because A103683(46) = 6.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000
• Rémy Sigrist, C program for A105214

Crossrefs

Cf. A103683.

Programs

C

See Links section.

Mathematica

f[s_] := Block[{k = 1, l = Take[s, -3]}, While[ Union[ GCD[k, l]] != {1} || MemberQ[s, k], k++]; Append[s, k]]; Take[Ordering@ Nest[f, {1, 2, 3}, 200], 41] (* Robert G. Wilson v, Jun 26 2011 *)

Extensions

More terms from Rémy Sigrist, Jan 05 2022