a(n) = n*(17*n - 13)/2.

Terms

a(0) =0a(1) =2a(2) =21a(3) =57a(4) =110a(5) =180a(6) =267a(7) =371a(8) =492a(9) =630a(10) =785a(11) =957a(12) =1146a(13) =1352a(14) =1575a(15) =1815a(16) =2072a(17) =2346a(18) =2637a(19) =2945a(20) =3270a(21) =3612a(22) =3971a(23) =4347a(24) =4740a(25) =5150a(26) =5577a(27) =6021a(28) =6482a(29) =6960