a(n) = n*(14*n-3).

Terms

a(0) =0a(1) =11a(2) =50a(3) =117a(4) =212a(5) =335a(6) =486a(7) =665a(8) =872a(9) =1107a(10) =1370a(11) =1661a(12) =1980a(13) =2327a(14) =2702a(15) =3105a(16) =3536a(17) =3995a(18) =4482a(19) =4997a(20) =5540a(21) =6111a(22) =6710a(23) =7337a(24) =7992a(25) =8675a(26) =9386a(27) =10125a(28) =10892a(29) =11687