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 A294069 The smallest digit of a(n+1) is strictly smaller than the largest digit of a(n) 1
 1, 10, 20, 11, 30, 2, 12, 13, 14, 3, 15, 4, 16, 5, 17, 6, 18, 7, 19, 8, 21, 31, 22, 40, 23, 24, 25, 26, 27, 28, 29, 32, 41, 33, 42, 34, 35, 36, 37, 38, 39, 43, 50, 44, 51, 45, 46, 47, 48, 49, 52, 53, 54, 60, 55, 61, 56, 57, 58, 59, 62, 63, 64, 65, 70, 66 (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 and not leading to a contradiction. From Robert G. Wilson v, Feb 07 2018: (Start) Inverse: 1, 6, 10, 12, 14, 16, 18, 20, 2, 4, 7, 8, 9, 11, 13, 15, 17, 19, 3, ..., . Permutation of the Integers. (End) LINKS Jean-Marc Falcoz, Table of n, a(n) for n = 1..10001 EXAMPLE The "0" of 10 is strictly < "1", which is the largest digit of 1; The "0" of 20 is strictly < "1", which is the largest digit of 10; The "1" of 11 is strictly < "2", which is the largest digit of 20; The "0" of 30 is strictly < "1", which is the largest digit of 11; The "2" of 2 is strictly < "3", which is the largest digit of 30; The "1" of 12 is strictly < "2", which is the largest digit of 2; etc. MATHEMATICA f[s_List] := Block[{k = 1, mx = Max@IntegerDigits@s[[-1]]}, While[MemberQ[s, k] || Min@IntegerDigits@k >= mx, k++]; Append[s, k]]; Nest[f, {1}, 80] (* Robert G. Wilson v, Feb 07 2018 *) CROSSREFS Cf. A002283, A011540, A284062-A284069. Sequence in context: A297353 A172503 A107859 * A249585 A067524 A069555 Adjacent sequences:  A294066 A294067 A294068 * A294070 A294071 A294072 KEYWORD base,nonn AUTHOR Eric Angelini and Jean-Marc Falcoz, Feb 07 2018 STATUS approved

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Last modified April 15 08:58 EDT 2021. Contains 342977 sequences. (Running on oeis4.)