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Lexicographically earliest sequence of positive distinct integers such that if a(n) steps over a(n) commas to the right, it is met by a term whose leftmost digit is odd.
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%I #14 Mar 23 2020 21:47:56

%S 1,3,2,4,5,6,7,9,8,10,11,12,13,14,15,16,17,18,19,30,20,31,21,32,22,33,

%T 23,34,24,35,25,36,26,37,27,38,28,39,29,40,50,41,42,51,43,44,52,45,46,

%U 53,47,48,54,49,55,56,57,58,59,60,61,70,62,63,71,64,65,72,66,67,73,68,69,74,75,76,77,78,79,90,80

%N Lexicographically earliest sequence of positive distinct integers such that if a(n) steps over a(n) commas to the right, it is met by a term whose leftmost digit is odd.

%e a(1) = 1 steps over 1 comma to be met by the odd digit 3;

%e a(2) = 3 steps over 3 commas to be met by the odd digit 5;

%e a(3) = 2 steps over 2 commas to be met by the same odd digit 5;

%e a(4) = 4 steps over 4 commas to be met by the odd digit 9;

%e a(5) = 5 steps over 5 commas to be met by the odd digit 1 (of 10);

%e a(6) = 6 steps over 6 commas to be met by the odd digit 1 (of 12); etc.

%Y Cf. A333404 (same idea but the leftmost digit is prime) and A333406 (the leftmost digit is nonprime).

%K base,nonn

%O 1,2

%A _Eric Angelini_ and _Carole Dubois_, Mar 23 2020