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

Terms

a(0) =1a(1) =3a(2) =7a(3) =15a(4) =28a(5) =45a(6) =55a(7) =21a(8) =-155a(9) =-696a(10) =-2051a(11) =-5013a(12) =-10745a(13) =-20373a(14) =-33284a(15) =-42231a(16) =-21545a(17) =97821a(18) =474985a(19) =1434000a(20) =3555097a(21) =7708515a(22) =14793463a(23) =24572583a(24) =32243644a(25) =20069445a(26) =-60546521a(27) =-323012523a(28) =-1000943027a(29) =-2518246440