Squares of even elements in Pascal's triangle A007318.

Terms

a(0) =4a(1) =16a(2) =36a(3) =16a(4) =100a(5) =100a(6) =36a(7) =400a(8) =36a(9) =64a(10) =784a(11) =3136a(12) =4900a(13) =3136a(14) =784a(15) =64a(16) =1296a(17) =7056a(18) =15876a(19) =15876a(20) =7056a(21) =1296a(22) =100a(23) =14400a(24) =44100a(25) =63504a(26) =44100a(27) =14400a(28) =100a(29) =108900