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 A028943 #33 Jul 08 2025 18:57:14 %S A028943 1,1,1,1,8,1,27,125,343,64,12167,24389,205379,2146689,30959144,274625, %T A028943 3574558889,50202571769,553185473329,4302115807744,578280195945297, %U A028943 1469451780501769,238670664494938073,13528653463047586625 %N A028943 Denominator of y coordinate of n*P where P is the generator [0,0] for rational points on curve y^2+y = x^3-x. %C A028943 We can take P = P[1] = [x_1, y_1] = [0,0]. Then P[n] = P[1]+P[n-1] = [x_n, y_n] for n >= 2. Sequence gives numerators of the x_n. - _N. J. A. Sloane_, Jan 27 2022 %D A028943 A. W. Knapp, Elliptic Curves, Princeton 1992, p. 77. %H A028943 Seiichi Manyama, <a href="/A028943/b028943.txt">Table of n, a(n) for n = 1..173</a> %H A028943 B. Mazur, <a href="https://doi.org/10.1090/S0273-0979-1986-15430-3">Arithmetic on curves</a>, Bull. Amer. Math. Soc. 14 (1986), 207-259; see p. 225. %F A028943 P=(0, 0), 2P=(1, 0), if kP=(a, b) then (k+1)P=(a'=(b^2-a^3)/a^2, b'=-1-b*a'/a). %e A028943 5P = (1/4, -5/8). %o A028943 (PARI) See A028940. %Y A028943 Cf. A028940, A028941, A028942. %K A028943 nonn,frac %O A028943 1,5 %A A028943 _N. J. A. Sloane_