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%I #9 Jul 01 2017 08:03:03
%S 1,2,3,4,5,6,7,8,9,81,21,22,31,23,41,24,51,25,61,26,71,27,82,32,33,42,
%T 34,52,35,62,36,72,37,83,43,44,53,45,63,46,73,47,84,54,55,64,56,74,57,
%U 85,65,66,75,67,86,76,77,87,88,91,28,92,38,93,48,94,58,95,68,96,78,97,89,811,29,812,39,813,49
%N Starting with a(1) = 1, a(n) = smallest nonnegative integer not yet in the sequence such that the first digit of a(n) is plus or minus one the last digit of a(n-1) plus or minus 1, with preference given +1 when possible. The digit 0 is not allowed.
%C If a(n-1) ends in 9, a(n) must begin with 8 (i.e., a forced decrease by 1).
%e 9 is followed by 81 in the sequence since there is no larger digit and 8 has already been used.
%Y Cf. A288945.
%K nonn,base
%O 1,2
%A _Enrique Navarrete_, Jun 19 2017
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