n^2 concatenated with (n+1)^2.

Terms

a(0) =1a(1) =14a(2) =49a(3) =916a(4) =1625a(5) =2536a(6) =3649a(7) =4964a(8) =6481a(9) =81100a(10) =100121a(11) =121144a(12) =144169a(13) =169196a(14) =196225a(15) =225256a(16) =256289a(17) =289324a(18) =324361a(19) =361400a(20) =400441a(21) =441484a(22) =484529a(23) =529576a(24) =576625a(25) =625676a(26) =676729a(27) =729784a(28) =784841a(29) =841900