A343279 - OEIS

%I #10 Apr 20 2021 18:45:33

%S 1,0,1,1,7,15,90,301,1701,7770,42525,246730,1323652,9321312,49329280,

%T 408741333,2141764053,20415995028,106175395755,1144614626805,

%U 5917584964655,71187132291275,366282500870286,4864251308951100,24930204590758260,362262620784874680

%N a(n) = Stirling2(n, floor(n/2)).

%C Number of partitions of an n-set into floor(n/2) nonempty subsets.

%t Table[StirlingS2[n, Floor[n/2]], {n, 0, 25}] (* _Amiram Eldar_, Apr 20 2021 *)

%o (PARI) a(n) = stirling(n, n\2, 2); \\ _Michel Marcus_, Apr 20 2021

%Y Cf. A007820, A048993, A129506, A343278.

%K nonn

%O 0,5

%A _Peter Luschny_, Apr 20 2021