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A115541
Numbers k such that the concatenation of 5*k with k gives a square.
0
1020408163265306122449, 4081632653061224489796, 9183673469387755102041, 106678449690695619239994950132559020325716449943188991289, 123721752304002019946976391869713420022724403484408534276
OFFSET
1,1
EXAMPLE
5102040816326530612245_1020408163265306122449 = 7142857142857142857143^2.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Jan 25 2006
STATUS
approved