OFFSET

1,1

COMMENTS

The sequence is infinite. Does a term a(n) exist such that from a(n) on a(n+1) is always a(n) + 1?

EXAMPLE

a(1) = 11 and Q(1) = 11 (with two 1s);

a(2) = 22 and Q(2) = 33 (with two 3s);

a(3) = 33 and Q(3) = 66 (with two 6s);

a(4) = 34 and Q(4) = 100 (with two 0s);

a(5) = 1 and Q(5) = 101 (with two 1s);

a(6) = 9 and Q(6) = 110 (with two 1s); etc.

MATHEMATICA

a[1]=11; a[n_]:=a[n]=(k=1; While[DuplicateFreeQ@IntegerDigits@ Total[Join[c=Array[a, n-1], {k}]]||MemberQ[c, k], k++]; k); Array[a, 70] (* Giorgos Kalogeropoulos, Jul 19 2023 *)

CROSSREFS

KEYWORD

base,nonn

AUTHOR

Eric Angelini, Jul 17 2023

STATUS

approved