a(n) = (3*n+2)*(3*n+5)/2.

Terms

a(0) =5a(1) =20a(2) =44a(3) =77a(4) =119a(5) =170a(6) =230a(7) =299a(8) =377a(9) =464a(10) =560a(11) =665a(12) =779a(13) =902a(14) =1034a(15) =1175a(16) =1325a(17) =1484a(18) =1652a(19) =1829a(20) =2015a(21) =2210a(22) =2414a(23) =2627a(24) =2849a(25) =3080a(26) =3320a(27) =3569a(28) =3827a(29) =4094