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 A057229 #12 Aug 21 2017 15:56:26 %S A057229 6,30,60,84,210,210,180,630,330,504,924,1320,546,1386,1560,2340,990, %T A057229 2730,840,2574,4620,1224,1716,3570,5610,7140,4290,1710,5016,7956,7980, %U A057229 2730,7854,10374,2310,11970,6630,10920,12540,4080,3036,11856,8970 %N A057229 a(n) = a*b = x*y with (a-b) = (x+y) = A020882(n) (a>b, a>0, b>0, x>0, y>0), gcd(a, b) = gcd(x, y) = 1. %C A057229 The quadratics in X, X^2 - S*X -+ P, where S=A020882(n), P=A057229(n) are each factorizable into two factors, all four being distinct: X^2 - S*X - P = (X - a)*(X + b). X^2 - S*X + P = (X - x)*(X - y). - _Lekraj Beedassy_, Apr 30 2004 %C A057229 Areas of primitive Pythagorean triangles sorted on hypotenuse A020882, then on perimeter A093507. - _Lekraj Beedassy_, Aug 18 2006 %H A057229 P. Yiu, <a href="http://math.fau.edu/yiu/RecreationalMathematics2003.pdf">Factorizable x^2 + px -+ q</a>, Recreational Mathematics, pp. 58/360. %e A057229 E.g. a(1)=6=6*1=3*2, (6-1)=(3+2)=5=A020882(1), gcd(6,1)=gcd(3,2)=1 %Y A057229 Cf. A020882, A008846, A024406, A024365. %K A057229 nonn %O A057229 0,1 %A A057229 _Naohiro Nomoto_, Sep 19 2000