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A006339 Least hypotenuse of n distinct Pythagorean triangles. 25
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Ray Chandler, Table of n, a(n) for n = 0..1438 (a(1439) exceeds 1000 digits).

Eric Weisstein's World of Mathematics, Circle Lattice Points

Eric Weisstein's World of Mathematics, Pythagorean Triple

MATHEMATICA

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 *)

CROSSREFS

Except for offset, same as A046112.

Sequence in context: A299958 A036156 A097756 * A046112 A032534 A036151

Adjacent sequences:  A006336 A006337 A006338 * A006340 A006341 A006342

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified November 28 11:11 EST 2020. Contains 338720 sequences. (Running on oeis4.)