a(n) = floor( 2^(n*(n-1)/2) / n! ).
A003091
a(n) = floor( 2^(n*(n-1)/2) / n! ).
Terms
- a(0) =1a(1) =1a(2) =1a(3) =2a(4) =8a(5) =45a(6) =416a(7) =6657a(8) =189372a(9) =9695869a(10) =902597327a(11) =154043277297
External references
- oeis: A003091
A003091
a(n) = floor( 2^(n*(n-1)/2) / n! ).