A032640 Numbers k such that k concatenated with itself is a lucky number.

3, 9, 21, 23, 51, 59, 63, 71, 75, 87, 89, 99, 105, 111, 117, 123, 129, 135, 143, 147, 153, 171, 173, 177, 191, 201, 237, 243, 255, 263, 285, 305, 309, 317, 327, 357, 363, 369, 371, 387, 389, 393, 431, 443, 459, 465, 467, 495, 497, 513, 521, 533, 561, 567, 573

Offset: 1

Author

Patrick De Geest, May 15 1998

Keywords

• nonn
• base

Examples

			123 is a member of the sequence since 123123 is a lucky number, i.e. A000959(10590) = 123123.
		

Links

• Kevin P. Thompson, Table of n, a(n) for n = 1..4215 (first 95 terms from Amiram Eldar)

Crossrefs

Cf. A000959, A032650.

Extensions

More terms from Sascha Kurz, Mar 24 2002