login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Least hypotenuse of primitive Pythagorean triangles with odd leg 2n+1.
15

%I #21 Apr 06 2017 21:27:30

%S 5,13,25,41,61,85,17,145,181,29,265,313,365,421,481,65,37,685,89,841,

%T 925,53,1105,1201,149,1405,73,185,1741,1861,65,97,2245,269,2521,2665,

%U 317,85,3121,3281,3445,157,425,3961,109,485,193,4705,101,5101,5305,137

%N Least hypotenuse of primitive Pythagorean triangles with odd leg 2n+1.

%C Ordered terms are A020882. - _Paul Curtz_, Sep 08 2008

%C Least value of x^2 + y^2 with gcd(x,y) = 1 such that y^2 - x^2 = 2n+1. - _Thomas Ordowski_, Apr 02 2017

%t f[n_] := Block[{k = 2}, While[c = Sqrt[(2n + 1)^2 + k^2]; ! IntegerQ@ c || GCD[2n + 1, c, k] > 1, k += 2]; c]; Array[f, 52] (* _Robert G. Wilson v_, Mar 18 2014 *)

%Y Cf. A020882, A088557, A088558, A096891, A096892, A096893, A096894, A096895, A096896, A096897, A096898, A096899, A096900.

%K nonn

%O 1,1

%A _Ray Chandler_, Jul 14 2004