OFFSET
1,2
FORMULA
a(n) = Sum_{i=1..n} gcd(i,2n-i) * mu(i)^2 * mu(2n-i)^2, where mu is the Möbius function (A008683).
MAPLE
MATHEMATICA
Table[Sum[GCD[k, 2*n - k]*MoebiusMu[k]^2 * MoebiusMu[2*n - k]^2, {k, 1,
n}], {n, 1, 50}] (* G. C. Greubel, Jan 05 2017 *)
PROG
(PARI) for(n=1, 50, print1(sum(k=1, n, gcd(k, 2*n-k) * (moebius(k))^2 *(moebius(2*n-k))^2), ", ")) \\ G. C. Greubel, Jan 05 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wesley Ivan Hurt, Jan 03 2017
STATUS
approved