Find the first number in the following series. (there may be more than one answer?)

?, 2 ,3 , 8, 30, 144, 840, 5760, 45360...

Each term in the sequence is the sum of two factorials
2=0!+1! 3=1!+2! 8=2!+3! 30=3!+4! 144=4!+5!
840=5!+6! 5760=6!+7! 45360=7!+8!

The first term would then be (-1)!+0! which is undefined since (-1)! is not defined.

Posted by Brian Smith on 2003-04-30 07:35:15