A308540 - OEIS

A308540

a(n) is the least nonnegative number whose digits do not appear in order (not necessarily consecutively) in the concatenation of all previous terms.

%I #15 Jul 24 2019 14:45:43

%S 0,1,2,3,4,5,6,7,8,9,10,22,33,44,55,66,77,88,99,100,332,554,776,998,

%T 1001,3322,5544,7766,9988,33220,33221,55445,77667,99889,332200,332211,

%U 776674,776675,3322008,3322009,7766741,7766755,33220088,33220099,77667411

%N a(n) is the least nonnegative number whose digits do not appear in order (not necessarily consecutively) in the concatenation of all previous terms.

%C This sequence is a variant of A048991.

%H Rémy Sigrist, <a href="/A308540/a308540.txt">C program for A308540</a>

%e The first terms are necessarily the one-digit numbers: a(1) = 0, a(2) = 1, ..., a(10) = 9.

%e The number 10 does not appear in "0123456789", hence a(11) = 10.

%e The digits of every number from 11 to 21 appear in order in "012345678910", but this is not the case for the number 22, hence a(12) = 22.

%o (C) See Links section.

%Y See A309340 for the binary variant.

%Y Cf. A048991.

%K nonn,base

%O 1,3

%A _Rémy Sigrist_, Jul 24 2019