a(n) = 13*n*(n+1).

Terms

a(0) =0a(1) =26a(2) =78a(3) =156a(4) =260a(5) =390a(6) =546a(7) =728a(8) =936a(9) =1170a(10) =1430a(11) =1716a(12) =2028a(13) =2366a(14) =2730a(15) =3120a(16) =3536a(17) =3978a(18) =4446a(19) =4940a(20) =5460a(21) =6006a(22) =6578a(23) =7176a(24) =7800a(25) =8450a(26) =9126a(27) =9828a(28) =10556a(29) =11310