A107780 a(1)=9, a(n) = smallest integer not previously used which contains a digit from a(n-1).

9, 19, 1, 10, 0, 20, 2, 12, 11, 13, 3, 23, 21, 14, 4, 24, 22, 25, 5, 15, 16, 6, 26, 27, 7, 17, 18, 8, 28, 29, 32, 30, 31, 33, 34, 35, 36, 37, 38, 39, 43, 40, 41, 42, 44, 45, 46, 47, 48, 49, 54, 50, 51, 52, 53, 55, 56, 57, 58, 59, 65, 60, 61, 62, 63, 64, 66, 67, 68, 69, 76, 70

Offset: 1

Author

Eric Angelini & Zak Seidov, May 24 2005

Keywords

• base
• nonn

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A107353 a(1)=0, A107772 a(1)=1, A107773 a(1)=2, A107774 a(1)=3, A107775 a(1)=4, A107776 a(1)=5, A107777 a(1)=6, A107778 a(1)=7, A107779 a(1)=8, A107781 a(1)=10.

Programs

Maple

S:= [$0..100]:
Res:= 9: S:= subs(9=NULL,S):
digs:= {9}:
while S <> [] do
  found:= false;
  for i from 1 to nops(S) while not found do
    ndigs:= convert(convert(S[i],base,10),set);
    if ndigs intersect digs <> {} then
      found:= true;
      Res:=Res, S[i];
      S:= subsop(i=NULL, S);
      digs:= ndigs;
    fi
  od;
  if not found then break fi;
od:
Res; # Robert Israel, Jan 22 2020

Mathematica

f[l_] := Block[{c = 0}, While[ MemberQ[l, c] || Intersection @@ IntegerDigits /@{Last[l], c}=={}, c++ ];Return[Append[l, c]]];Nest[f, {9}, 70] (* Ray Chandler, Jul 19 2005 *)