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A006339
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Least hypotenuse of n distinct Pythagorean triangles.
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30
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1, 5, 25, 125, 65, 3125, 15625, 325, 390625, 1953125, 1625, 48828125, 4225, 1105, 6103515625, 30517578125, 40625, 21125, 3814697265625, 203125, 95367431640625, 476837158203125, 5525, 11920928955078125, 274625, 5078125, 1490116119384765625, 528125, 25390625, 186264514923095703125
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OFFSET
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0,2
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LINKS
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MATHEMATICA
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oneModFourPrimes[1] = 5;
oneModFourPrimes[n_] := oneModFourPrimes[n] = NestWhile[NextPrime, NextPrime[oneModFourPrimes[n - 1]], Mod[#, 4] != 1 & ];
factorizations[1, limit_] = {{}};
factorizations[n_, limit_] := factorizations[n, limit] = Join @@ Table[Prepend[#, d]& /@ factorizations[n/d, d], {d, Select[Rest[Divisors[n]], # <= limit & ]}];
leastHypotenuse[n_] := Min[(Times @@ (Array[oneModFourPrimes, Length[#]]^((# - 1)/2)) & ) /@ factorizations[2*n + 1, 2*n + 1]];
Array[leastHypotenuse, 30, 0]
(* Albert H. Mao, Jan 06 2012 *)
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CROSSREFS
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Except for offset, same as A046112.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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