A054215 Squares that are concatenations of two consecutive decreasing numbers.

8281, 82428241, 98029801, 538277538276, 998002998001, 7783702677837025, 9998000299980001, 79225472657922547264, 86432513458643251344, 92237976109223797609, 99998000029999800001, 106710893290106710893289

Offset: 1

Author

Patrick De Geest, Feb 15 2000

Keywords

• nonn
• base

Comments

Infinitely many terms of this sequence are provided by A168624(k)^2 for k>0. - Bruno Berselli, Mar 13 2018

Examples

			E.g. '8242' + '8242-1' gives 82428241 which is 9079^2.
		

References

• Luca, Florian, and Pantelimon Stănică. "Perfect Squares as Concatenation of Consecutive Integers." The American Mathematical Monthly 126.8 (2019): 728-734.

Crossrefs

Cf. A054214, A054216, A030465, A030466, A030467, A020339, A020340.

Formula

a(n) = concatenation of A054214(n) and A054214(n)-1. - Max Alekseyev, May 14 2007

Extensions

More terms from Max Alekseyev, May 14 2007

82848241 corrected to 82428241 by Dominick Cancilla, Jul 21 2010