a(n) = a(n-1) + 2*n^2 with a(1) = 1.

Terms

a(0) =1a(1) =9a(2) =27a(3) =59a(4) =109a(5) =181a(6) =279a(7) =407a(8) =569a(9) =769a(10) =1011a(11) =1299a(12) =1637a(13) =2029a(14) =2479a(15) =2991a(16) =3569a(17) =4217a(18) =4939a(19) =5739a(20) =6621a(21) =7589a(22) =8647a(23) =9799a(24) =11049a(25) =12401a(26) =13859a(27) =15427a(28) =17109a(29) =18909