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 A299823 To concatenate all terms, to concatenate the odd rank terms or to concatenate the even rank terms produces the same result. 1
 12, 121, 1, 2, 21, 11, 122, 22, 111, 1111, 1222, 222, 211, 2111, 11111, 111112, 12222, 2222, 2221, 221, 1211, 12111, 111111, 1111111, 1111121, 1112, 22222, 122222, 222222, 2222221, 1221, 2211, 121112, 21112, 11111111, 111111111, 1111111111, 11111111111, 11121 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The sequence starts with a(1) = 12 and is always extended with the smallest integer not yet present and not leading to a contradiction. This is the lexicographically first sequence having this property, except the trivial 1, 11, 111, 1111, 11111,... Trying a(1) = 10 gives a sequence with terms having leading zeroes -- which is not admitted. All terms belong to A007931. - Rémy Sigrist, Dec 08 2018 LINKS Rémy Sigrist, Table of n, a(n) for n = 1..10000 Rémy Sigrist, Perl program for A299823 EXAMPLE The first five terms of the sequence are: 12,121,1,2,21 The first five odd-ranked terms are: 12,1,21,122,111 The first five even-ranked terms are: 121,2,11,22,1111 ... and we see that those three partitions start with the same concatenation: 121211221... PROG (Perl) See Links section. CROSSREFS Cf. A007931. Sequence in context: A012442 A262204 A037097 * A222634 A018204 A176779 Adjacent sequences:  A299820 A299821 A299822 * A299824 A299825 A299826 KEYWORD nonn,base,look AUTHOR Eric Angelini, Feb 19 2018 EXTENSIONS More terms from Rémy Sigrist, Dec 08 2018 STATUS approved

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Last modified December 12 09:36 EST 2019. Contains 329953 sequences. (Running on oeis4.)