a(1) = 1, a(n) = a(n-1) if n == 1 (mod 4), otherwise a(n) = n * a(n-1) for n >= 2.
A123145
a(1) = 1, a(n) = a(n-1) if n == 1 (mod 4), otherwise a(n) = n * a(n-1) for n >= 2.
Terms
- a(0) =1a(1) =2a(2) =6a(3) =24a(4) =24a(5) =144a(6) =1008a(7) =8064a(8) =8064a(9) =80640a(10) =887040a(11) =10644480a(12) =10644480a(13) =149022720a(14) =2235340800a(15) =35765452800a(16) =35765452800a(17) =643778150400
External references
- oeis: A123145