cp's OEIS Frontend

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.

%I A331631 #10 Jan 25 2020 09:19:18
%S A331631 1,3,9,27,81,2,6,18,54,162,4,12,36,108,324,5,15,7,21,63,189,567,8,24,
%T A331631 72,216,648,10,30,90,270,810,11,33,99,297,891,2673,8019,24057,72171,
%U A331631 216513,649539,1948617,5845851,17537553,52612659,157837977,473513931,1420541793,4261625379,12784876137,38354628411,13,39
%N 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.
%C A331631 This is conjectured to be a permutation of the positive integers (see the Crossrefs section).
%H A331631 Carole Dubois, <a href="/A331631/b331631.txt">Table of n, a(n) for n = 1..14999</a>
%e A331631 The process begins like this:
%e A331631 Initially S = 1 is the smallest missing number, so we have:
%e A331631 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, ...
%Y A331631 Cf. A331440 (where one adjoins 2*S, 4*S, 8*S, 16*S, ... to the sequence).
%K A331631 base,nonn
%O A331631 1,2
%A A331631 _Eric Angelini_ and _Carole Dubois_, Jan 23 2020