Factorial numbers
1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800, 39916800, 479001600, 6227020800, 87178291200, 1307674368000, 20922789888000, 355687428096000, 6402373705728000, 121645100408832000, 2432902008176640000, 51090942171709440000, 1124000727777607680000
OFFSET
0
COMMENTS
Number of permutations of n elements.
FORMULAS
a(n) = Product_{k=1..n} k
a(n) = Sum_{k=0..n} (-1)^k * (n-k)^n * binomial(n, k)
PROGRAMS
PARI/GP
a(n) = factorial(n);
Sidef
say 30.of { .factorial }