a(n) = n + (n+1)^2.

Terms

a(0) =1a(1) =5a(2) =11a(3) =19a(4) =29a(5) =41a(6) =55a(7) =71a(8) =89a(9) =109a(10) =131a(11) =155a(12) =181a(13) =209a(14) =239a(15) =271a(16) =305a(17) =341a(18) =379a(19) =419a(20) =461a(21) =505a(22) =551a(23) =599a(24) =649a(25) =701a(26) =755a(27) =811a(28) =869a(29) =929