OFFSET
0,5
COMMENTS
Appears to be all 10's starting at a(169). - T. D. Noe, Apr 01 2014
LINKS
T. D. Noe, Table of n, a(n) for n = 0..1000
FORMULA
a(n) = A043537(2^n). - R. J. Mathar, Mar 16 2008
EXAMPLE
a(16) = 3 because 2^16 = 65536, which contains 3 distinct decimal digits [3,5,6].
MAPLE
A043537 := proc(n) nops(convert(convert(n, base, 10), set)) ; end: A137214 := proc(n) A043537(2^n) ; end: seq(A137214(n), n=0..120) ; # R. J. Mathar, Mar 16 2008
a:=proc(n) options operator, arrow: nops(convert(convert(2^n, base, 10), set)) end proc: seq(a(n), n=0..80); # Emeric Deutsch, Apr 02 2008
MATHEMATICA
Table[Length[Union[IntegerDigits[2^n]]], {n, 0, 100}] (* T. D. Noe, Apr 01 2014 *)
PROG
(Python)
def a(n): return len(set(str(2**n)))
print([a(n) for n in range(99)]) # Michael S. Branicky, Jul 23 2021
CROSSREFS
KEYWORD
easy,nonn,base
AUTHOR
Ctibor O. Zizka, Mar 06 2008
EXTENSIONS
More terms from R. J. Mathar and Emeric Deutsch, Mar 16 2008
STATUS
approved