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A282116
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Numbers k such that k-1/2*R(k) and k+1/2*R(k) are both positive squares, where R(k) is the digits reverse of k.
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0
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OFFSET
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1,1
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COMMENTS
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a(7), if it exists, is larger than 2*10^15. - Giovanni Resta, Jul 14 2017
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LINKS
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EXAMPLE
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(468 - 1/2*864)^(1/2) = (36)^(1/2) = 6 and (468 +1/2*864)^(1/2) = (900)^(1/2) = 30.
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MAPLE
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R:=proc(w) local x, y, z; x:=w; y:=0; for z from 1 to ilog10(x)+1 do y:=10*y+(x mod 10); x:=trunc(x/10); od; y; end:
P:=proc(q, k) local n; for n from 1 to q do
if n>k*R(n) then if frac(sqrt(n-k*R(n)))=0 and frac(sqrt(n+k*R(n)))=0
then print(n); fi; fi; od; end: P(10^9, 1/2);
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CROSSREFS
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KEYWORD
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nonn,base,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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