This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A290501 #19 Dec 30 2019 14:29:00
%S A290501 48828125,97656250,146484375,195312500,292968750,341796875,390625000,
%T A290501 439453125,537109375,585937500,683593750,781250000,878906250,
%U A290501 927734375,1025390625,1074218750,1123046875,1171875000,1318359375,1367187500,1513671875,1562500000,1611328125
%N A290501 Hypotenuses for which there exist exactly 11 distinct integer triangles.
%C A290501 Numbers whose square is decomposable in 11 different ways into the sum of two nonzero squares: these are those with only one prime divisor of the form 4k+1 with multiplicity eleven.
%H A290501 Ray Chandler, <a href="/A290501/b290501.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 terms from Hamdi Sahloul)
%F A290501 Terms are obtained by the product A004144(k)*A002144(p)^11 for k, p > 0 ordered by increasing values.
%e A290501 a(1) = 48828125 = 5^11, a(5) = 292968750 = 2*3*5^11, a(101) = 9375000000 = 2^6*3*5^11.
%t A290501 r[a_]:={b, c}/.{ToRules[Reduce[0<b<c && a^2 == b^2 + c^2, {b, c}, Integers]]}; Select[Range[9375000000], Length[r[#]] == 11 &] (* _Vincenzo Librandi_, Mar 01 2016 *)
%Y A290501 Cf. A002144, A006339, A046080, A046109, A083025.
%Y A290501 Cf. A004144 (0), A084645 (1), A084646 (2), A084647 (3), A084648 (4), A084649 (5), A097219 (6), A097101 (7), A290499 (8), A290500 (9), A097225 (10), A097226 (12), A097102 (13), A290502 (14), A290503 (15), A097238 (16), A097239 (17), A290504 (18), A290505 (19), A097103 (22), A097244 (31), A097245 (37), A097282 (40), A097626 (67).
%K A290501 nonn
%O A290501 1,1
%A A290501 _Hamdi Sahloul_, Aug 04 2017