A171073 Smallest positive integer a(n) not yet in the sequence and sharing no digit with n, (n-1) or (n+1) in its decimal representation.

3, 4, 1, 2, 7, 8, 5, 6, 22, 23, 9, 40, 50, 20, 27, 24, 25, 26, 33, 34, 35, 44, 10, 11, 13, 14, 15, 16, 17, 45, 46, 47, 18, 12, 19, 21, 29, 41, 51, 28, 36, 55, 56, 60, 30, 31, 32, 52, 37, 38, 39, 48, 61, 62, 70, 42, 43, 63, 71, 72, 49, 54, 57, 77, 73, 80, 53, 100, 111, 58, 59, 64, 65

Offset

1,1

Comments

Sequence has 1234567 terms, ending with a(1234567) = 9990990999. - Michael S. Branicky, Apr 08 2023

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000

Michael S. Branicky, Python program

Mathematica

f[s_List] := Block[{k = 1, len = Length@s}, id = Union@ Flatten[ IntegerDigits /@ {len, len + 1, len + 2}]; While[ MemberQ[s, k] || Intersection[id, IntegerDigits@k] != {}, k++ ]; Append[s, k]]; Nest[f, {}, 73] (* Robert G. Wilson v, Sep 25 2010 *)

Prog

(Python) # see linked program generating full sequence

Crossrefs

Cf. A171072. - Robert G. Wilson v, Sep 25 2010

Sequence in context: A021971 A260822 A256008 * A021297 A124909 A348354

Adjacent sequences: A171070 A171071 A171072 * A171074 A171075 A171076

Keyword

nonn,base,fini

Author

N. J. A. Sloane, Sep 06 2010, based on an email from Eric Angelini, Jun 30 2010

Extensions

a(22) inserted, a(25) and a(26) corrected, etc. by Robert G. Wilson v, Sep 25 2010

a(42) corrected by Michael S. Branicky, Apr 08 2023

Status

approved