A381918 Kaprekar numbers that are the concatenation of two consecutive numbers.

45, 2223, 2728, 4950, 148149, 351352, 499500, 11111112, 38883889, 49995000, 63636364, 74747475, 75247525, 86358636, 4756047561, 4999950000, 5867158672, 6111061111, 8888888889, 9132791328, 104247104248, 164983164984, 178321178322, 195156195157, 230769230770, 269230269231

Offset: 1

Author

Shyam Sunder Gupta, Mar 10 2025

Keywords

• base
• nonn

Comments

Since all numbers 4950, 449500, 49995000, ... are Kaprekar numbers, there are infinitely many terms.

Examples

			If the number 351 is concatenated with the next number, 352, we get a Kaprekar number, 351352. It can be verified that 351352^2 = 123448227904, and 123448 + 227904 = 351352.
		

Links

• Shyam Sunder Gupta, Table of n, a(n) for n = 1..2143
• Shyam Sunder Gupta, On Some Marvellous Numbers of Kaprekar, Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 9, 275-315.

Crossrefs

Intersection of A006886 and A001704.

Cf. A030466.