A378986 a(n) = 2*phi(2*n) - 2*n, where phi is Euler totient function.

0, 0, -2, 0, -2, -4, -2, 0, -6, -4, -2, -8, -2, -4, -14, 0, -2, -12, -2, -8, -18, -4, -2, -16, -10, -4, -18, -8, -2, -28, -2, 0, -26, -4, -22, -24, -2, -4, -30, -16, -2, -36, -2, -8, -42, -4, -2, -32, -14, -20, -38, -8, -2, -36, -30, -16, -42, -4, -2, -56, -2, -4, -54, 0, -34, -52, -2, -8, -50, -44, -2, -48, -2, -4

Offset: 1

Author

Antti Karttunen, Dec 14 2024

Keywords

• sign

Links

• Antti Karttunen, Table of n, a(n) for n = 1..32769

Crossrefs

Even bisection of A083254, and of A297114.

First row of A379011.

Cf. A000010, A008683, A033879, A062570, A176095, A378978.

Cf. also A378987.

Programs

PARI

A378986(n) = (2*eulerphi(2*n)-(2*n));

Formula

a(n) = 2*A000010(2*n) - 2*n.

a(n) = A083254(2*n) = A297114(2*n).

a(n) = -2*A176095(n).

a(n) = Sum_{d|2n} A008683(d)*A033879(2*n/d).