OFFSET
1,1
COMMENTS
Of 1110 perfect powers < 1000000, 259 have distinct digits.
For large number of digits, the distinct-digit pp's consists of surprisingly small part of all pp's (shown in brackets) 4(4), 8(8), 18(28), 46(84), 76(242), 107(744), 126(2284), 101(7096), 84(22179), 0(69561).
EXAMPLE
a(3)=18 because there are exactly 18 three-digit perfect powers: 125, 128, 169, 196, 216, 243, 256, 289, 324, 361, 512, 529, 576, 625, 729, 784, 841, 961.
CROSSREFS
KEYWORD
fini,full,nonn,base
AUTHOR
Zak Seidov, Oct 13 2002
STATUS
approved