Expansion of x*(1+3*x)/ ( (1-4*x)*(1+x+x^2)).

Terms

a(0) =0a(1) =1a(2) =6a(3) =21a(4) =85a(5) =342a(6) =1365a(7) =5461a(8) =21846a(9) =87381a(10) =349525a(11) =1398102a(12) =5592405a(13) =22369621a(14) =89478486a(15) =357913941a(16) =1431655765a(17) =5726623062a(18) =22906492245a(19) =91625968981a(20) =366503875926