A302589 - OEIS

A302589

The digital sum of a(n) is not a substring of a(n+1), a(n+1) being the smallest integer not yet present in the sequence that doesn't lead to a contradiction.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 11, 13, 12, 14, 16, 15, 17, 19, 18, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 40, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 60, 51, 52, 53, 54, 55, 56, 57, 58, 59, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 80, 71, 72, 73, 74, 75, 76, 77

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OFFSET

1,2

COMMENTS

a(1) = 1, and for n > 1 a(n) is the smallest integer not yet present in the sequence such that the digital sum of a(n-1) is not a substring of the decimal digits of a(n).

LINKS

Lars Blomberg, Table of n, a(n) for n = 1..10000

EXAMPLE

The digital sum of 1 is 1, so a(2) = 2 is the first unused number not containing a "1"; the digital sum of 2 is 2, so a(3) = 3 is the first unused number not containing a "2"; ...; the digital sum of 10 is 1, so a(11) = 20 is the first unused number not containing a "2" (2 is already used); etc.

CROSSREFS

Cf. A173821 (where a(n) IS a substring of a(n+1)).

Sequence in context: A089583 A264979 A319726 * A375755 A210538 A247143

Adjacent sequences: A302586 A302587 A302588 * A302590 A302591 A302592

KEYWORD

nonn,base

AUTHOR

Eric Angelini and Lars Blomberg, Apr 10 2018

STATUS

approved