Start with 1, add 1, subtract 2, multiply by 3, add 4, subtract 5, multiply by 6, add 7, etc.

Terms

a(0) =1a(1) =2a(2) =0a(3) =0a(4) =4a(5) =-1a(6) =-6a(7) =1a(8) =-7a(9) =-63a(10) =-53a(11) =-64a(12) =-768a(13) =-755a(14) =-769a(15) =-11535a(16) =-11519a(17) =-11536a(18) =-207648a(19) =-207629a(20) =-207649a(21) =-4360629a(22) =-4360607a(23) =-4360630a(24) =-104655120a(25) =-104655095a(26) =-104655121a(27) =-2825688267a(28) =-2825688239a(29) =-2825688268