1/2 the number of colorings of a 3 X 3 square array with n colors.

Terms

a(0) =1a(1) =123a(2) =4806a(3) =71410a(4) =583455a(5) =3232341a(6) =13675228a(7) =47502036a(8) =141991245a(9) =377162335a(10) =910842306a(11) =2033854758a(12) =4253012491a(13) =8411348505a(14) =15856955640a(15) =28673921896a(16) =49991146713a(17) =84387303171a(18) =138412872190a(19) =221253017370a(20) =345558093111a(21) =528471784093a(22) =792890261076