OFFSET
1,9
COMMENTS
Every positive integers occurs infinitely many times. See A297770 for a guide to related sequences.
LINKS
Clark Kimberling, Table of n, a(n) for n = 1..10000
EXAMPLE
6643 in base-9: 1,0,1,0,1; five runs, of which 2 are distinct, so that a(6643) = 2.
MATHEMATICA
b = 9; s[n_] := Length[Union[Split[IntegerDigits[n, b]]]]
Table[s[n], {n, 1, 200}]
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Clark Kimberling, Jan 29 2018
STATUS
approved