Return double factorial
n(n-2)...(5)(3)(1), n>0, odd n!! = n(n-2)...(6)(4)(2), n>0, even 1 , n = -1, or n = 0
For example
6!! = (6)(4)(2) = 48
Neither n = -1, nor n = 0 are tested.
2725 Solvers
1137 Solvers
Sum the elements in either diagonal of a square matrix
144 Solvers
264 Solvers
6 Solvers