A032650 Lucky numbers that are concatenations of a number k with itself.

33, 99, 2121, 2323, 5151, 5959, 6363, 7171, 7575, 8787, 8989, 9999, 105105, 111111, 117117, 123123, 129129, 135135, 143143, 147147, 153153, 171171, 173173, 177177, 191191, 201201, 237237, 243243, 255255, 263263, 285285, 305305, 309309, 317317

Offset: 1

Author

Patrick De Geest, May 15 1998

Keywords

• nonn
• base

Links

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

Crossrefs

Intersection of A000959 and A020338.

Cf. A032640.

Formula

a(n) = A032640(n) || A032640(n), where || denotes concatenation. - Kevin P. Thompson, Nov 09 2021

Extensions

More terms from Sascha Kurz, Mar 24 2002

Edited by Charles R Greathouse IV, Apr 26 2010