1,1

Double factorials 0!! and 1!! are not considered distinct. Note that double factorial (n!!) is different from (n!)!.

Table of n, a(n) for n=1..53.

947 is prime and 947 = 9!! + 2!!.

Cf. A006882, A115651, A115652, A115654.

Sequence in context: A216509 A075237 A040062 * A042997 A220815 A171600

Adjacent sequences: A115650 A115651 A115652 * A115654 A115655 A115656

nonn

Giovanni Resta, Jan 28 2006

approved