a(n) = n*(5*n^2 - 3)/2.

Terms

a(0) =0a(1) =1a(2) =17a(3) =63a(4) =154a(5) =305a(6) =531a(7) =847a(8) =1268a(9) =1809a(10) =2485a(11) =3311a(12) =4302a(13) =5473a(14) =6839a(15) =8415a(16) =10216a(17) =12257a(18) =14553a(19) =17119a(20) =19970a(21) =23121a(22) =26587a(23) =30383a(24) =34524a(25) =39025a(26) =43901a(27) =49167a(28) =54838a(29) =60929