G.f.: (108*x^2+27*x+1)/(1+2*x-6*x^2-27*x^3).

Terms

a(0) =1a(1) =25a(2) =64a(3) =49a(4) =961a(5) =100a(6) =6889a(7) =12769a(8) =18496a(9) =225625a(10) =4489a(11) =1844164a(12) =2430481a(13) =6325225a(14) =51724864a(15) =124609a(16) =480881041a(17) =435556900a(18) =2017536889a(19) =11562055729a(20) =741146176a(21) =122363538025a(22) =71895305689a(23) =610401563524