OFFSET
1,4
LINKS
Eric Weisstein's World of Mathematics, Liouville Function
FORMULA
G.f.: (1/(1 - x)) * ((theta_3(x) - 1) / 2 - Sum_{k>=2} lambda(k-1) * x^k / (1 - x^k)).
a(n) = floor(sqrt(n)) - Sum_{k=1..n} Sum_{d|k, d > 1} lambda(d-1).
Sum_{k=1..n} mu(k) * a(floor(n/k)) = lambda(n).
MATHEMATICA
Table[Sum[LiouvilleLambda[Floor[n/k]], {k, 1, n}], {n, 1, 85}]
Table[Floor[Sqrt[n]] - Sum[DivisorSum[k, LiouvilleLambda[# - 1] &, # > 1 &], {k, 1, n}], {n, 1, 85}]
nmax = 85; CoefficientList[Series[(1/(1 - x)) ((EllipticTheta[3, 0, x] - 1)/2 - Sum[LiouvilleLambda[k - 1] x^k/(1 - x^k), {k, 2, nmax}]), {x, 0, nmax}], x] // Rest
PROG
(PARI) a(n) = sum(k=1, n, (-1)^bigomega(n\k)); \\ Michel Marcus, Feb 14 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 14 2020
STATUS
approved