Inverse of A038303, and generalization of A130595.

Terms

a(0) =1a(1) =10a(2) =-1a(3) =100a(4) =-20a(5) =1a(6) =1000a(7) =-300a(8) =30a(9) =-1a(10) =10000a(11) =-4000a(12) =600a(13) =-40a(14) =1a(15) =100000a(16) =-50000a(17) =10000a(18) =-1000a(19) =50a(20) =-1a(21) =1000000a(22) =-600000a(23) =150000a(24) =-20000a(25) =1500a(26) =-60a(27) =1a(28) =10000000a(29) =-7000000