Definition:Kaprekar Number/Sequence
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Definition
The sequence of Kaprekar numbers begins:
- $1, 9, 45, 55, 99, 297, 703, 999, 2223, 2728, 4879, 4950, 5050, 5292, 7272, 7777, 9999, 17344, \ldots$
This sequence is A006886 in the On-Line Encyclopedia of Integer Sequences (N. J. A. Sloane (Ed.), 2008).
Some sources do not include such numbers as $4879$ and $5292$:
- $1, 9, 45, 55, 99, 297, 703, 999, 2223, 2728, 4950, 5050, 7272, 7777, 9999, 17344, \ldots$
where the $2$nd of the $2$ parts begins with one or more leading zeroes:
- $4879^2 = 23 \, 804 \, 641 \to 238 + 04641 = 4879$
- $5292^2 = 28 \, 005 \, 264 \to 28 + 005264 = 5292$
This sequence is A053816 in the On-Line Encyclopedia of Integer Sequences (N. J. A. Sloane (Ed.), 2008).
Sources
- 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $297$
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $297$