a(n) = 20*n^2 + 1.

Terms

a(0) =1a(1) =21a(2) =81a(3) =181a(4) =321a(5) =501a(6) =721a(7) =981a(8) =1281a(9) =1621a(10) =2001a(11) =2421a(12) =2881a(13) =3381a(14) =3921a(15) =4501a(16) =5121a(17) =5781a(18) =6481a(19) =7221a(20) =8001a(21) =8821a(22) =9681a(23) =10581a(24) =11521a(25) =12501a(26) =13521a(27) =14581a(28) =15681a(29) =16821