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A271186
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Odd integers k such that k^k + 1 is the sum of 2 nonzero squares.
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1
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OFFSET
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1,2
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LINKS
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EXAMPLE
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9 is a term because 9^9 + 1 = 1457^2 + 19629^2.
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MATHEMATICA
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Select[Range[1, 25, 2], Length[PowersRepresentations[#^# + 1, 2, 2] /. {0, _} -> Nothing] > 0 &] (* Michael De Vlieger, Apr 01 2016 *)
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PROG
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(PARI) a014566(n) = n^n+1;
isA000404(n) = { for( i=1, #n=factor(n)~%4, n[1, i]==3 && n[2, i]%2 && return); n && ( vecmin(n[1, ])==1 || (n[1, 1]==2 && n[2, 1]%2))}
for(n=1, 1e2, if(isA000404(a014566(n)) && n%2 == 1, print1(n, ", ")));
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CROSSREFS
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KEYWORD
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nonn,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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