OFFSET
0,7
EXAMPLE
n = 19: reverse(2^19) = 882425 = 5^2*47*751, so a(19) = 3.
n = 38: reverse(2^38) = 449609778472 = 2^3*56201222309, so a(38) = 2. - Sean A. Irvine, Sep 26 2023
MATHEMATICA
a[n_] := PrimeNu[IntegerReverse[2^n]]; Array[a, 100, 0] (* Amiram Eldar, Oct 02 2024 *)
PROG
(PARI) a(n) = omega(fromdigits(Vecrev(digits(2^n)))); \\ Amiram Eldar, Oct 02 2024
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Jan 06 2005
EXTENSIONS
a(38) corrected by Sean A. Irvine, Sep 26 2023
STATUS
approved