a(n) = (3*n + 2)^6.

Terms

a(0) =64a(1) =15625a(2) =262144a(3) =1771561a(4) =7529536a(5) =24137569a(6) =64000000a(7) =148035889a(8) =308915776a(9) =594823321a(10) =1073741824a(11) =1838265625a(12) =3010936384a(13) =4750104241a(14) =7256313856a(15) =10779215329a(16) =15625000000a(17) =22164361129a(18) =30840979456a(19) =42180533641a(20) =56800235584a(21) =75418890625a(22) =98867482624a(23) =128100283921