A concatenation sequence, or concatenated number sequence, is an integer sequence constructed by concatenating digits onto previous sequence terms.
Examples are summarized in the following table.
| sequence | OEIS | limiting constant | terms |
| Smarandache numbers | A007908 | Champernowne constant | 1, 12, 123, 1234, 12345, 123456, ... |
| Smarandache-Wellin numbers | A019518 | Copeland-Erdős constant | 2, 23, 235, 2357, 235711, ... |
| concatenation of binary digits of positive integers | A058935 | binary Champernowne constant | 1, 110, 11011, 11011100, 11011100101, ... |
| concatenation of prime counting function values | A366033 | prime-counting concatenation constant | 0, 01, 012, 0122, 01223, 012233, 0122334, ... |
