Expansion of (1-x+sqrt(1-6x+x^2))/2 in powers of x.

Terms

a(0) =1a(1) =-2a(2) =-2a(3) =-6a(4) =-22a(5) =-90a(6) =-394a(7) =-1806a(8) =-8558a(9) =-41586a(10) =-206098a(11) =-1037718a(12) =-5293446a(13) =-27297738a(14) =-142078746a(15) =-745387038a(16) =-3937603038a(17) =-20927156706a(18) =-111818026018a(19) =-600318853926