a(n) = n*(11*n + 3)/2.

Terms

a(0) =0a(1) =7a(2) =25a(3) =54a(4) =94a(5) =145a(6) =207a(7) =280a(8) =364a(9) =459a(10) =565a(11) =682a(12) =810a(13) =949a(14) =1099a(15) =1260a(16) =1432a(17) =1615a(18) =1809a(19) =2014a(20) =2230a(21) =2457a(22) =2695a(23) =2944a(24) =3204a(25) =3475a(26) =3757a(27) =4050a(28) =4354a(29) =4669