Alternately add and multiply.

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =2a(5) =2a(6) =4a(7) =8a(8) =12a(9) =96a(10) =108a(11) =10368a(12) =10476a(13) =108615168a(14) =108625644