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

Terms

a(0) =1a(1) =0a(2) =4a(3) =4a(4) =20a(5) =36a(6) =116a(7) =260a(8) =724a(9) =1764a(10) =4660a(11) =11716a(12) =30356a(13) =77220a(14) =198644a(15) =507524a(16) =1302100a(17) =3332196a(18) =8540596a(19) =21869380a(20) =56031764a(21) =143509284a(22) =367636340a(23) =941673476a(24) =2412218836a(25) =6178912740a(26) =15827788084a(27) =40543439044a(28) =103854591380