Pair up the numbers.

Terms

a(0) =12a(1) =34a(2) =56a(3) =78a(4) =910a(5) =1112a(6) =1314a(7) =1516a(8) =1718a(9) =1920a(10) =2122a(11) =2324a(12) =2526a(13) =2728a(14) =2930a(15) =3132a(16) =3334a(17) =3536a(18) =3738a(19) =3940a(20) =4142a(21) =4344a(22) =4546a(23) =4748a(24) =4950a(25) =5152a(26) =5354a(27) =5556a(28) =5758a(29) =5960