A339820 a(n) = phi(A019565(n)), where phi is Euler totient function.

1, 1, 2, 2, 4, 4, 8, 8, 6, 6, 12, 12, 24, 24, 48, 48, 10, 10, 20, 20, 40, 40, 80, 80, 60, 60, 120, 120, 240, 240, 480, 480, 12, 12, 24, 24, 48, 48, 96, 96, 72, 72, 144, 144, 288, 288, 576, 576, 120, 120, 240, 240, 480, 480, 960, 960, 720, 720, 1440, 1440, 2880, 2880, 5760, 5760, 16, 16, 32, 32, 64, 64, 128, 128

Offset: 0

Author

Antti Karttunen, Dec 18 2020

Keywords

• nonn

Crossrefs

Cf. A000010, A019565, A339821 (bisection).

Cf. also A324650, A339809.

Programs

PARI

A339820(n) = { my(m=1, p=1); while(n>0, p = nextprime(1+p); if(n%2, m *= (p-1)); n >>= 1); (m); };

Formula

If 2n = 2^e1 + 2^e2 + ... + 2^ek [e1 ... ek distinct], then a(n) = A006093(e1) * A006093(e2) * ... * A006093(ek).

a(n) = A000010(A019565(n)).