Squares of odd elements in Pascal triangle.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =9a(7) =9a(8) =1a(9) =1a(10) =1a(11) =1a(12) =25a(13) =25a(14) =1a(15) =1a(16) =225a(17) =225a(18) =1a(19) =1a(20) =49a(21) =441a(22) =1225a(23) =1225a(24) =441a(25) =49a(26) =1a(27) =1a(28) =1a(29) =1