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 A121705 #11 Sep 15 2024 03:44:03
%S A121705 0,1,1,2,0,5,3,4,2,11,5,10,0,25,7,24,15,20,10,55,25,50,38,41,0,125,35,
%T A121705 120,44,117,75,100,29,278,50,275,125,250,190,205,0,625,175,600,220,
%U A121705 585,336,527,375,500,145,1390,250,1375,625,1250,718,1199,950,1025,0,3125
%N A121705 Triangle read by rows: 5^n expressed as the sum of two squares.
%e A121705 5^n expressed as the sum of two squares: 5^n = x^2 + y^2, 0 <= x < y.
%e A121705 Number of solutions for n=0,1,...: a(n)=1,1,2,2,3,3,4,4,5,5,6,6,...
%e A121705 Triangle of solutions for n=0,1,...:
%e A121705 {x,y}
%e A121705 {{0,1}},
%e A121705 {{1,2}},
%e A121705 {{0,5},{3,4}},
%e A121705 {{2,11},{5,10}},
%e A121705 {{0,25},{7,24},{15,20}},
%e A121705 {{10,55},{25,50},{38,41}},
%e A121705 {{0,125},{35,120},{44,117},{75,100}},
%e A121705 {{29,278},{50,275},{125,250},{190,205}},
%e A121705 {{0,625},{175,600},{220,585},{336,527},{375,500}},
%e A121705 {{145,1390},{250,1375},{625,1250},{718,1199},{950,1025}},
%e A121705 {{0,3125},{237,3116},{875,3000},{1100,2925},{1680,2635},{1875,2500}},
%e A121705 {{725,6950},{1250,6875},{2642,6469},{3125,6250},{3590,5995},{4750,5125}},
%e A121705 {{0,15625},{1185,15580},{4375,15000},{5500,14625},{8400,13175},{9375,12500},{10296,11753}}
%Y A121705 Cf. A004431, A006496, A024507, A120905.
%K A121705 nonn,tabf
%O A121705 0,4
%A A121705 _Zak Seidov_, Sep 10 2006