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A277998 Lexicographically first sequence (with no duplicates) where the last digit of a(n) added to the first digit of a(n+1) equals 10. 1
1, 9, 11, 91, 92, 8, 2, 81, 93, 7, 3, 71, 94, 6, 4, 61, 95, 5, 51, 96, 41, 97, 31, 98, 21, 99, 12, 82, 83, 72, 84, 62, 85, 52, 86, 42, 87, 32, 88, 22, 89, 13, 73, 74, 63, 75, 53, 76, 43, 77, 33, 78, 23, 79, 14, 64, 65, 54, 66, 44, 67, 34, 68, 24, 69, 15, 55, 56, 45, 57, 35, 58, 25, 59, 16, 46, 47, 36, 48, 26, 49, 17, 37, 38, 27, 39, 18, 28, 29, 19, 101, 901, 902, 801, 903, 701, 904, 601, 905, 501, 906, 401, 907, 301, 908, 201 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The sequence starts with a(1) = 1 and was always extended with the smallest integer not yet present that does not lead to a contradiction.

LINKS

Jean-Marc Falcoz, Table of n, a(n) for n = 1..10001

EXAMPLE

The sequence begins with 1, 9, 11, 91, 92, 8, 2, 81, 93, 71... The two digits that border the first comma are 1 and 9 that sum up to 10 as required; the 2nd comma is bordered by 9 and 1; the 3rd one by 1 and 9 again; the 4th one by 1 and 9 too; the 5th one by 2 and 8; the 6th one by 8 and 2; the 7th one by 2 and 8 again; the 8th one by 1 and 9; the 9th one by 3 and 7, etc.

CROSSREFS

Sequence in context: A195992 A108687 A038301 * A289288 A137016 A053886

Adjacent sequences:  A277995 A277996 A277997 * A277999 A278000 A278001

KEYWORD

nonn,base

AUTHOR

Eric Angelini and Jean-Marc Falcoz, Nov 08 2016

STATUS

approved

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Last modified October 16 15:22 EDT 2021. Contains 348042 sequences. (Running on oeis4.)