A331631 Let S = smallest missing positive number, adjoin S, 3*S, 9*S, 27*S, 81*S, ... to the sequence until reaching a term that has S as a substring; reset S to the smallest missing positive number, repeat.

1, 3, 9, 27, 81, 2, 6, 18, 54, 162, 4, 12, 36, 108, 324, 5, 15, 7, 21, 63, 189, 567, 8, 24, 72, 216, 648, 10, 30, 90, 270, 810, 11, 33, 99, 297, 891, 2673, 8019, 24057, 72171, 216513, 649539, 1948617, 5845851, 17537553, 52612659, 157837977, 473513931, 1420541793, 4261625379, 12784876137, 38354628411, 13, 39

Offset: 1

Author

Eric Angelini and Carole Dubois, Jan 23 2020

Keywords

• base
• nonn

Comments

This is conjectured to be a permutation of the positive integers (see the Crossrefs section).

Examples

			The process begins like this:
Initially S = 1 is the smallest missing number, so we have:
S = 1, 3, 9, 27, 81, stop (because 81 contains S), S = 2, 6, 18, 54, 162, stop, S = 4, 12, 36, 108, 324, stop, S = 5, 15, stop, S = 7, 21, 63, 189, 567, ...
		

Links

• Carole Dubois, Table of n, a(n) for n = 1..14999

Crossrefs

Cf. A331440 (where one adjoins 2*S, 4*S, 8*S, 16*S, ... to the sequence).