A089015 - OEIS

%I #18 Dec 25 2023 08:24:15

%S 3,33,105,315,9009,2145,1155,3045

%N Least odd short leg of n primitive Pythagorean triangles.

%C a(9) is greater than 30000000, if it exists. a(12) through a(16) are 204435, 26565, 15015, 41055, 153153. - _Joshua Zucker_, May 13 2006

%e a(3)=105 because 105 is the first odd short leg of the 3 primitive Pythagorean triples, viz. (105, 208, 233), (105, 608, 617), (105, 5512, 5513), followed by such triples of primitive Pythagorean triangles each starting with 165, 195, 231, 255, 273, 285, 429, 715, 765, 819, 935, 969, 1001, ...

%e Similarly, a(4)=315 because the group of 4 odd-short-leg primitive Pythagorean triangles (315, 572, 653), (315, 988, 1037), (315, 1972, 1997), (315, 49612, 49613) precedes all such groups of 4 primitive Pythagorean triangles each starting with 385, 455, 495, 693, ...

%Y Cf. A083883.

%K hard,more,nonn

%O 1,1

%A _Lekraj Beedassy_, Nov 04 2003

%E More terms from _Joshua Zucker_, May 13 2006