login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

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
1, 9, 81, 2, 18, 82, 3, 27, 173, 4, 36, 264, 5, 45, 355, 6, 54, 446, 7, 63, 537, 8, 72, 628, 10, 90, 810, 11, 89, 711, 12, 88, 712, 13, 87, 713, 14, 86, 714, 15, 85, 715, 16, 84, 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
OFFSET
1,2
LINKS
EXAMPLE
a(1) + a(2) = 1 + 9 = 10 with 1 the leftmost digit of both 1 and 10;
a(2) + a(3) = 9 + 81 = 90 with 9 the leftmost digit of both 9 and 90;
a(3) + a(4) = 81 + 2 = 83 with 8 the leftmost digit of both 81 and 83;
a(4) + a(5) = 2 + 18 = 20 with 2 the leftmost digit of both 2 and 20;
a(5) + a(6) = 18 + 82 = 100 with 1 the leftmost digit of both 18 and 100; etc.
CROSSREFS
Sequence in context: A317052 A363420 A352386 * A117817 A328760 A228591
KEYWORD
base,nonn
AUTHOR
Eric Angelini and Carole Dubois, Feb 20 2020
STATUS
approved