A341036 - OEIS

%I #22 Mar 13 2021 10:58:51

%S 1,2,5,19,129,1306,16813,262181,4783059,100000214,2357947701,

%T 61917372083,1792160394049,56693912393474,1946195068811453,

%U 72057594039243049,2862423051509815809,121439531096661117354,5480386857784802185957

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

%t a[n_] := Sum[GCD[k, n]^(k - 2), {k, 1, n}]; Array[a, 20] (* _Amiram Eldar_, Mar 13 2021 *)

%o (PARI) a(n) = sum(k=1, n, gcd(k, n)^(k-2));

%Y Cf. A000010, A018804, A342370, A342432, A342449.

%K nonn

%O 1,2

%A _Seiichi Manyama_, Mar 13 2021