p^2 + (p+2)^2 - 1 where (p,p+2) is the n-th twin prime pair.

Terms

a(0) =33a(1) =73a(2) =289a(3) =649a(4) =1801a(5) =3529a(6) =7201a(7) =10369a(8) =20809a(9) =23329a(10) =38089a(11) =45001a(12) =64801a(13) =73729a(14) =78409a(15) =103969a(16) =115201a(17) =145801a(18) =159049a(19) =194689a(20) =242209a(21) =352801a(22) =373249a(23) =426889a(24) =544969a(25) =649801a(26) =720001a(27) =763849a(28) =824329a(29) =871201