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A247263
Positive numbers not divisible by 10 whose squares remain squares when prefixed with 1000.
5
375, 2371875, 6816208478590683385931482169914619837072677910327911376953125, 140221743281593822163509288486586064542459780568606220185756683349609375, 818488127823449514709977488133381451695186814276894438080489635467529296875
OFFSET
1,1
LINKS
EXAMPLE
375^2 = 140625 and 1000140625 is square.
PROG
(PARI)
for(n=1, 10^20, if(n^2%100&&issquare(10^(#Str(n^2)+3)+n^2), print1(n^2, ", "))) \\ Derek Orr, Sep 13 2014
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Chai Wah Wu, Sep 11 2014
STATUS
approved