OFFSET
0,4
LINKS
Henri Lifchitz, Table of n, a(n) for n = 0..67
Eric Weisstein's World of Mathematics, Liouville Function.
FORMULA
a(n) = A002819(2^n).
MATHEMATICA
Table[Sum[LiouvilleLambda[k], {k, 1, 2^n}], {n, 0, 15}]
PROG
(PARI) a(n) = sum(i=1, 2^n, (-1)^bigomega(i));
(Python)
from math import isqrt
from functools import lru_cache
@lru_cache(maxsize=None)
def A002321(n):
if n == 0:
return 0
c, j = n, 2
k1 = n//j
while k1 > 1:
j2 = n//k1 + 1
c += (j2-j)*A002321(k1)
j, k1 = j2, n//j2
return j-c
def A390483(n):
m = 1<<n
c, j, k1 = isqrt(m)+1, 1, m
while k1 > 1:
j2 = isqrt(m//k1) + 1
c += (j2-j)*A002321(k1)
j, k1 = j2, m//j2**2
return c-j # Chai Wah Wu, Nov 13 2025
CROSSREFS
KEYWORD
sign
AUTHOR
Henri Lifchitz, Nov 07 2025
STATUS
approved
