A181540 a(n) = Sum_{k=0..n} gcd(n,k)*phi(k).

0, 1, 3, 8, 13, 26, 29, 54, 59, 84, 93, 142, 139, 202, 195, 244, 259, 352, 327, 444, 433, 508, 505, 656, 639, 776, 719, 866, 889, 1054, 1057, 1208, 1151, 1332, 1255, 1624, 1575, 1728, 1579, 1886, 2011, 2130, 2159, 2348, 2329, 2716, 2329

Offset: 0

Author

Peter Luschny, Oct 29 2010

Keywords

• nonn

Comments

Row sums of triangle A181538.

Crossrefs

Cf. A181538.

Programs

Maple

A181540 := n -> add(igcd(n,k)*numtheory[phi](k),k=0..n);

Mathematica

Table[Sum[GCD[n,k]EulerPhi[k],{k,0,n}],{n,0,50}] (* Harvey P. Dale, Jul 12 2020 *)

PARI

a(n) = sum(k=1, n, gcd(n, k)*eulerphi(k)); \\ Michel Marcus, May 18 2018