A338647 a(n) = Sum_{k=1..n} 2^(k/gcd(n,k) - 1).

1, 2, 4, 7, 16, 22, 64, 92, 223, 342, 1024, 1132, 4096, 5462, 13534, 21937, 65536, 70978, 262144, 333472, 890590, 1398102, 4194304, 4528402, 16236031, 22369622, 57522106, 88435312, 268435456, 272976502, 1073741824, 1431677702, 3679303390, 5726623062, 16490405374, 18543422953

Offset: 1

Author

Ilya Gutkovskiy, Apr 22 2021

Keywords

• nonn

Crossrefs

Cf. A011782, A034738, A054432, A057661, A130586.

Programs

Mathematica

Table[Sum[2^(k/GCD[n, k] - 1), {k, 1, n}], {n, 1, 36}]

PARI

a(n) = sum(k=1, n, 2^(k/gcd(n,k) - 1)); \\ Michel Marcus, Apr 22 2021

Formula

a(n) = Sum_{d|n} A054432(d).