a(n) = 1 + 27n + 252n^2 + 882n^3 + 1029n^4.

Terms

a(0) =1a(1) =2191a(2) =24583a(3) =109513a(4) =324013a(5) =759811a(6) =1533331a(7) =2785693a(8) =4682713a(9) =7414903a(10) =11197471a(11) =16270321a(12) =22898053a(13) =31369963a(14) =42000043a(15) =55126981a(16) =71114161a(17) =90349663a(18) =113246263a(19) =140241433a(20) =171797341a(21) =208400851a(22) =250563523a(23) =298821613a(24) =353736073a(25) =415892551a(26) =485901391