3*n^2-2*n+6.

Terms

a(0) =6a(1) =7a(2) =14a(3) =27a(4) =46a(5) =71a(6) =102a(7) =139a(8) =182a(9) =231a(10) =286a(11) =347a(12) =414a(13) =487a(14) =566a(15) =651a(16) =742a(17) =839a(18) =942a(19) =1051a(20) =1166a(21) =1287a(22) =1414a(23) =1547a(24) =1686a(25) =1831a(26) =1982a(27) =2139a(28) =2302a(29) =2471