Question

Help with math problem- finding first four terms of a sequence with a factorial. An=2(n+1)!

Answer 1

$a_1=2\cdot(1+1)!=2\cdot2!=2\cdot1\cdot2=\boxed{4}\\\\ a_2=2\cdot(2+1)!=2\cdot3!=2\cdot1\cdot2\cdot3=\boxed{12}\\\\ a_3=2\cdot(3+1)!=2\cdot4!=2\cdot1\cdot2\cdot3\cdot4=\boxed{48}\\\\ a_4=2\cdot(4+1)!=2\cdot5!=2\cdot1\cdot2\cdot3\cdot4\cdot5=\boxed{240}$