a(n) = 3*n^4.

Terms

a(0) =0a(1) =3a(2) =48a(3) =243a(4) =768a(5) =1875a(6) =3888a(7) =7203a(8) =12288a(9) =19683a(10) =30000a(11) =43923a(12) =62208a(13) =85683a(14) =115248a(15) =151875a(16) =196608a(17) =250563a(18) =314928a(19) =390963a(20) =480000a(21) =583443a(22) =702768a(23) =839523a(24) =995328a(25) =1171875a(26) =1370928a(27) =1594323a(28) =1843968a(29) =2121843