A090512 Least multiple of n such that the n-th concatenation is a multiple of n. The (previous) (n-1)-th term is so chosen that the n-th term exists.

1, 2, 3, 12, 15, 30, 7, 128, 9, 50, 22, 36, 26, 28, 15, 1232, 85, 414, 19, 500, 84, 462, 69, 120, 200, 364, 81, 532, 29, 810, 31, 10784, 198, 272, 70, 1476, 148, 266, 39, 2160, 123, 1890, 43, 308, 855, 368, 94, 336, 49, 1550, 153, 52, 1484, 648, 220, 3416, 1026, 3886

Offset

1,2

Comments

If n+1 has any prime divisors other than 2 or 5, then a(n) is to be chosen so that the concatenation of first n terms is a multiple of those primes (including multiplicity). - David Wasserman, Dec 20 2005

Links

Table of n, a(n) for n=1..58.

Example

a(5) = 15 because if it were 5 or 10, a(6) would not exist.

Crossrefs

Sequence in context: A173079 A173903 A154785 * A076175 A289870 A067780

Adjacent sequences: A090509 A090510 A090511 * A090513 A090514 A090515

Keyword

base,nonn

Author

Amarnath Murthy, Dec 06 2003

Extensions

More terms from David Wasserman, Dec 20 2005

Status

approved