A054615 a(n) = Sum_{d|n} phi(d)*8^(n/d).

0, 8, 72, 528, 4176, 32800, 262800, 2097200, 16781472, 134218800, 1073774880, 8589934672, 68719748256, 549755813984, 4398048608688, 35184372156480, 281474993496384, 2251799813685376, 18014398644225456, 144115188075856016

Offset: 0

Author

N. J. A. Sloane, Apr 16 2000

Keywords

• nonn

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..1000

Crossrefs

Column k=8 of A185651.

Cf. A054627.

Programs

PARI

a(n) = sumdiv(n, d, eulerphi(d)*8^(n/d)); \\ Michel Marcus, Jul 11 2021

Formula

a(n) = Sum_{k=1..n} 8^gcd(n,k). - Ilya Gutkovskiy, Apr 16 2021