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 A332702 Lexicographically earliest sequence of distinct positive terms such that the leftmost digit of a(n) and the leftmost digit of a(n) + a(n+1) are the same. 1

%I #9 Feb 22 2020 10:38:44

%S 1,9,81,2,18,82,3,27,173,4,36,264,5,45,355,6,54,446,7,63,537,8,72,628,

%T 10,90,810,11,89,711,12,88,712,13,87,713,14,86,714,15,85,715,16,84,

%U 716,17,83,717,19,91,809,20,180,820,21,179,821,22,178,822,23,177,823,24,176,824,25,175,825,26

%N Lexicographically earliest sequence of distinct positive terms such that the leftmost digit of a(n) and the leftmost digit of a(n) + a(n+1) are the same.

%H Carole Dubois, <a href="/A332702/b332702.txt">Table of n, a(n) for n = 1..1000</a>

%e a(1) + a(2) = 1 + 9 = 10 with 1 the leftmost digit of both 1 and 10;

%e a(2) + a(3) = 9 + 81 = 90 with 9 the leftmost digit of both 9 and 90;

%e a(3) + a(4) = 81 + 2 = 83 with 8 the leftmost digit of both 81 and 83;

%e a(4) + a(5) = 2 + 18 = 20 with 2 the leftmost digit of both 2 and 20;

%e a(5) + a(6) = 18 + 82 = 100 with 1 the leftmost digit of both 18 and 100; etc.

%K base,nonn

%O 1,2

%A _Eric Angelini_ and _Carole Dubois_, Feb 20 2020

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Last modified September 9 22:43 EDT 2024. Contains 375765 sequences. (Running on oeis4.)