OFFSET
1,5
FORMULA
a(n) = Sum_{i=1..n} 1 - mu(2n-i)^2 * mu(i)^2, where mu is the Möbius function (A008683).
a(n) = n - A280226(n). - Wesley Ivan Hurt, Dec 11 2023
MATHEMATICA
Table[Sum[1 - MoebiusMu[2 n - i]^2*MoebiusMu[i]^2, {i, n}], {n, 100}]
PROG
(Magma) [&+[(1-MoebiusMu(2*n-k)^2*MoebiusMu(k)^2): k in [1..n]]: n in [1..70]]; // Vincenzo Librandi, Apr 09 2018
(PARI) a(n) = sum(i=1, n, 1 - moebius(2*n-i)^2*moebius(i)^2); \\ Michel Marcus, Apr 09 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Apr 06 2018
STATUS
approved