A247262
Positive squares not ending in 00 that remain squares when prefixed with 100.
Original entry on oeis.org
126609965386962890625, 2251582387232059478759765625, 35195816356873080847263336181640625, 507081064881263080149056017398834228515625, 6906141992927910623080625169910490512847900390625, 90266080419142123943961730174907133914530277252197265625
Offset: 1
126609965386962890625 and 100126609965386962890625 are both squares.
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for(n=1,10^30,if(n^2%100&&issquare(10^(#Str(n^2)+2)+n^2),print1(n^2,", "))) \\ Derek Orr, Sep 13 2014
A247264
Smallest positive number not divisible by 10 whose square remains a square when prefixed with 10^n.
Original entry on oeis.org
15, 75, 11252109375, 375, 9694963627295445503856592180983186990852118469774723052978515625, 6841439843263141047421876154427540653587129781953990459442138671875
Offset: 0
a(0) = 15 since 15^2 = 225 and 1225 is square and 15 is the smallest number not ending in 0 with this property. a(3) = 375 since 375^2 = 140625 and 1000140625 is square and 375 is the smallest number not ending in 0 with this property.
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a(n)=k=1;while(k^2%100==0||!issquare(10^(#Str(k^2)+n)+k^2),k++);k^2
n=0;while(n<10,print1(a(n),", ");n++) \\ Derek Orr, Sep 13 2014
Showing 1-2 of 2 results.
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