Zseq (version 0.2.2)

Factorial.Double: Double Factorial of even or odd numbers

Description

Under OEIS A000165 and A001147, a Double Factorial is the factorial of numbers with same parity. For example, if \(n=5\), then \(n!!=5*3*1\). Please be aware that this function returns either even- or odd-valued numbers' double factorials per the use of odd parameter.

Usage

Factorial.Double(n, gmp = TRUE, odd = TRUE)

Value

a vector of length n containing first entries from the sequence.

Arguments

n

the number of first n entries from the sequence.

gmp

a logical; TRUE to use large number representation, FALSE otherwise.

odd

a logical; TRUE for double factorial of odd numbers, FALSE for even numbers.

See Also

Factorial

Examples

# \donttest{
## generate first 10 double factorials
print(Factorial.Double(10))
# }