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factdouble

Double factorial.

v = factdouble(number)

Returns n!! — the product of every other integer (skipping by 2): odd n gives 1·3·5·...·n, even n gives 2·4·6·...·n.

factdouble(7) % 105 (1·3·5·7)
factdouble(6) % 48 (2·4·6)
  • fact — Factorial.