A054613 a(n) = Sum_{d|n} phi(d)*6^(n/d).

0, 6, 42, 228, 1344, 7800, 46956, 279972, 1681008, 10078164, 60474120, 362797116, 2176832112, 13060694088, 78364444284, 470185001040, 2821111589856, 16926659444832, 101559966840108, 609359740010604, 3656158500550080

Offset: 0

Author

N. J. A. Sloane, Apr 16 2000

Keywords

• nonn

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..1285

Crossrefs

Column k=6 of A185651.

Cf. A054625.

Programs

PARI

a(n) = if(n==0, 0, sumdiv(n, d, eulerphi(d)*6^(n/d))); \\ Altug Alkan, Mar 16 2018

Formula

a(n) = n * A054625(n).

a(n) = Sum_{k=1..n} 6^gcd(n,k). - Ilya Gutkovskiy, Apr 16 2021