A243997 a(n) = phi(sigma(n) - phi(n) - d(n)), where phi(n) is the Euler totient function, sigma(n) the sum of divisors of n and d(n) the number of divisors of n.

1, 0, 0, 1, 0, 2, 0, 6, 2, 4, 0, 6, 0, 6, 4, 6, 0, 18, 0, 12, 8, 10, 0, 20, 4, 12, 6, 18, 0, 24, 0, 40, 8, 16, 8, 24, 0, 18, 12, 20, 0, 36, 0, 28, 16, 22, 0, 42, 4, 66, 12, 32, 0, 46, 12, 40, 16, 28, 0, 48, 0, 30, 30, 40, 16, 56, 0, 40, 16, 48, 0, 104, 0, 36

Offset: 1

Author

Paolo P. Lava, Jun 19 2014

Keywords

• nonn
• easy

Comments

Subset of A243995.

a(p)=0 if p is prime.

Examples

			sigma(72) = 195, phi(72) = 24, d(72) = 12 and phi(195 - 24 - 12) = 104.
		

Links

• Paolo P. Lava, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000005, A000010, A000203, A243995.

Programs

Maple

with(numtheory): P:=proc(q) local n;
for n from 1 to q do print(phi(sigma(n)-phi(n)-tau(n)));
od; end: P(100);