A372608 - OEIS

%I #15 May 09 2024 09:01:38

%S 1,3,10,18,44,40,114,124,198,192,430,292,708,540,704,888,1552,954,

%T 2178,1456,1980,2080,3806,2216,4220,3480,4734,4056,7588,3560,9270,

%U 6960,7920,7840,9936,7296,15588,10980,13056,11120,21240,10128,24570,16360,17880,19360,32062

%N a(n) = Sum_{k=1..n} phi(n*k).

%H Seiichi Manyama, <a href="/A372608/b372608.txt">Table of n, a(n) for n = 1..10000</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/TotientFunction.html">Totient Function</a>.

%F a(n) = A372606(n,n).

%F a(n) = A000010(n) * A070639(n).

%o (PARI) a(n) = sum(k=1, n, eulerphi(k*n));

%Y Main diagonal of A372606.

%Y Cf. A000010, A070639.

%K nonn

%O 1,2

%A _Seiichi Manyama_, May 07 2024