A139079 Smallest number not yet in the sequence that contains the last digit of the previous term, with a(1) = 1.

1, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 101, 11, 12, 2, 21, 13, 3, 23, 31, 14, 4, 24, 34, 41, 15, 5, 25, 35, 45, 51, 16, 6, 26, 36, 46, 56, 61, 17, 7, 27, 37, 47, 57, 67, 71, 18, 8, 28, 38, 48, 58, 68, 78, 81, 19, 9, 29, 39, 49, 59, 69, 79, 89, 91, 102, 22, 32, 42, 52, 62, 72

Offset: 1

Author

Franklin T. Adams-Watters, Jan 31 2009

Keywords

• base
• nonn

Comments

This is a permutation of the positive integers.

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A076654, A125886.

Programs

Maple

a := [1] ; for n from 2 to 100 do ldig := op(-1,a) mod 10 ; for c from 1 do if c in a then ; else dgs := convert(c,base,10) ; if ldig in dgs then a := [op(a),c] ; break; fi; fi; od: od: print(a) ; # R. J. Mathar

Mathematica

s={1};Do[k=1;Until[ContainsAny[IntegerDigits[k],Take[IntegerDigits[s[[-1]]],-1]]&&!MemberQ[s,k],k++];AppendTo[s,k],{m,71}];s (* James C. McMahon, Jun 28 2025 *)