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

0,3

Links

Table of n, a(n) for n=0..71.

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)).

Prog

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

Crossrefs

Cf. A000010, A019565, A339821 (bisection).

Cf. also A324650, A339809.

Sequence in context: A347444 A120541 A190172 * A287293 A059867 A359182

Adjacent sequences: A339817 A339818 A339819 * A339821 A339822 A339823

Keyword

nonn

Author

Antti Karttunen, Dec 18 2020

Status

approved