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A054215 Squares that are concatenations of two consecutive decreasing numbers. 9
8281, 82428241, 98029801, 538277538276, 998002998001, 7783702677837025, 9998000299980001, 79225472657922547264, 86432513458643251344, 92237976109223797609, 99998000029999800001, 106710893290106710893289 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Infinitely many terms of this sequence are provided by A168624(k)^2 for k>0. - Bruno Berselli, Mar 13 2018
REFERENCES
Luca, Florian, and Pantelimon Stănică. "Perfect Squares as Concatenation of Consecutive Integers." The American Mathematical Monthly 126.8 (2019): 728-734.
LINKS
FORMULA
a(n) = concatenation of A054214(n) and A054214(n)-1. - Max Alekseyev, May 14 2007
EXAMPLE
E.g. '8242' + '8242-1' gives 82428241 which is 9079^2.
CROSSREFS
Sequence in context: A064014 A203881 A145527 * A031589 A031769 A280872
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Feb 15 2000
EXTENSIONS
More terms from Max Alekseyev, May 14 2007
82848241 corrected to 82428241 by Dominick Cancilla, Jul 21 2010
STATUS
approved

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Last modified March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)