OFFSET
1,2
COMMENTS
FORMULA
The sum of first 2^n terms is (5*20^n + 38*10^n - 95*2^n + 1420)/171. Giovanni Resta, Mar 25 2017
MATHEMATICA
Join @@ (FromDigits /@ Tuples[{1, 9}, #] & /@ Range[5]) (* Giovanni Resta, Mar 25 2017 *)
PROG
(Magma) [n: n in [1..20000] | Set(IntegerToSequence(n, 10)) subset {1, 9}]
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Mar 25 2017
STATUS
approved