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 A271186 Odd integers n such that n^n + 1 is the sum of 2 nonzero squares. 0
 1, 9, 17, 25, 49 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE 9 is a term because 9^9 + 1 = 1457^2 + 19629^2. MATHEMATICA Select[Range[1, 25, 2], Length[PowersRepresentations[#^# + 1, 2, 2] /. {0, _} -> Nothing] > 0 &]  (* Michael De Vlieger, Apr 01 2016 *) PROG (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, ", "))); CROSSREFS Cf. A000404, A014566. Sequence in context: A211432 A211422 A035198 * A253705 A056233 A260264 Adjacent sequences:  A271183 A271184 A271185 * A271187 A271188 A271189 KEYWORD nonn,more AUTHOR Altug Alkan, Apr 01 2016 STATUS approved

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Last modified August 5 05:22 EDT 2020. Contains 336209 sequences. (Running on oeis4.)