A352391 - OEIS

%I #13 May 09 2022 11:01:33

%S 1,2,4,8,16,5,11,6,7,18,12,19,20,28,17,15,14,23,21,31,9,27,26,33,22,

%T 37,36,32,10,13,25,24,47,46,55,3,30,42,48,35,38,40,52,29,56,43,49,62,

%U 50,39,59,58,45,57,72,60,64,68,41,65,71,66,51,54,67,77,53,75,61,69,82,87,34,92,78,88,63,85,73

%N Lexicographically earliest sequence of distinct positive integers such that the last digit of |a(n) - a(n+1)| is the n-th digit of the sequence.

%e |a(1) - a(2)| = |1 - 2| = 1 and the terminal 1 of 1 is the 1st digit of the sequence;

%e |a(2) - a(3)| = |2 - 4| = 2 and the terminal 2 of 2 is the 2nd digit of the sequence;

%e |a(3) - a(4)| = |4 - 8| = 4 and the terminal 4 of 4 is the 3rd digit of the sequence;

%e |a(4) - a(5)| = |8 - 16| = 8 and the terminal 8 of 8 is the 4th digit of the sequence;

%e |a(5) - a(6)| = |16 - 5| = 11 and the terminal 1 of 11 is the 5th digit of the sequence; etc.

%t a[1]=1;a[n_]:=a[n]=Block[{k=1},While[MemberQ[s=Array[a,n-1],k]||Mod[Abs[a[n-1]-k],10]!=Flatten[IntegerDigits/@s][[n-1]],k++];k];Array[a,79] (* _Giorgos Kalogeropoulos_, May 09 2022 *)

%Y Cf. A352386, A352387, A352389, A352390.

%K base,nonn

%O 1,2

%A _Eric Angelini_ and _Carole Dubois_, Mar 14 2022