A293516 a(n) = phi(n) - 2*phi(phi(n)), where phi = Euler totient function, A000010.

-1, -1, 0, 0, 0, 0, 2, 0, 2, 0, 2, 0, 4, 2, 0, 0, 0, 2, 6, 0, 4, 2, 2, 0, 4, 4, 6, 4, 4, 0, 14, 0, 4, 0, 8, 4, 12, 6, 8, 0, 8, 4, 18, 4, 8, 2, 2, 0, 18, 4, 0, 8, 4, 6, 8, 8, 12, 4, 2, 0, 28, 14, 12, 0, 16, 4, 26, 0, 4, 8, 22, 8, 24, 12, 8, 12, 28, 8, 30, 0, 18, 8, 2, 8, 0, 18, 8, 8, 8, 8, 24, 4, 28, 2, 24, 0, 32

Offset

1,7

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Formula

a(n) = A000010(n) - 2*A010554(n).

a(n) = A070556(n) - A010554(n).

a(n) = -A083254(A000010(n)).

Prog

(PARI) A293516(n) = (eulerphi(n) - 2*eulerphi(eulerphi(n)));

Crossrefs

Cf. A000010, A010554, A051953, A070556, A083254, A295660.

Cf. A003401 (gives the positions of zeros after the two initial -1's).

Sequence in context: A317839 A137899 A369382 * A333808 A307692 A300548

Adjacent sequences: A293513 A293514 A293515 * A293517 A293518 A293519

Keyword

sign

Author

Antti Karttunen, Nov 27 2017

Status

approved