A308463 - OEIS

%I #9 May 29 2019 03:30:06

%S 1,1,4,7,51,16,876,2045,15475,15256,678569,2006863,27644436,46065293,

%T 669225640,5235101739,82864869803,234937438645,5832742205056,

%U 25117329128165,235703526149476,1886712616836675,44152005855084345,102153081219673712,3428690854204959151

%N a(n) = Sum_{k=1..n, gcd(n,k) = 1} Stirling2(n,k).

%t a[n_] := Sum[If[GCD[n, k] == 1, StirlingS2[n, k] , 0], {k, 1, n}]; Table[a[n], {n, 1, 25}]

%o (PARI) a(n) = sum(k=1, n, if (gcd(n,k)==1, stirling(n, k, 2))); \\ _Michel Marcus_, May 28 2019

%Y Cf. A000110, A008277, A056188, A096314, A308037.

%K nonn

%O 1,3

%A _Ilya Gutkovskiy_, May 28 2019