OFFSET
0,4
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..6643
FORMULA
a(n) = A070228(n) - 1 for n > 1. - Amiram Eldar, May 19 2022
EXAMPLE
For n=3, the perfect powers smaller than 2^3=8 are: 1 and 4. So a(3) = 2.
MATHEMATICA
Join[{0, 1}, Table[-Sum[MoebiusMu[x]*Floor[2^(n/x) - 1], {x, 2, n}], {n, 2, 50}]]
PROG
(PARI) a(n) = sum(k=1, 2^n-1, (k==1) || ispower(k)); \\ Michel Marcus, Apr 11 2016
(Python)
from sympy import mobius, integer_nthroot
def A188951(n): return int(sum(mobius(x)*(1-integer_nthroot(1<<n, x)[0]) for x in range(2, n+1))) if n!=1 else 1 # Chai Wah Wu, Aug 13 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
T. D. Noe, Apr 20 2011
STATUS
approved