Concatenation of n and the n-th composite number.

Terms

a(0) =14a(1) =26a(2) =38a(3) =49a(4) =510a(5) =612a(6) =714a(7) =815a(8) =916a(9) =1018a(10) =1120a(11) =1221a(12) =1322a(13) =1424a(14) =1525a(15) =1626a(16) =1727a(17) =1828a(18) =1930a(19) =2032a(20) =2133a(21) =2234a(22) =2335a(23) =2436a(24) =2538a(25) =2639a(26) =2740a(27) =2842a(28) =2944a(29) =3045