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 A096955 #20 Jan 03 2024 17:17:40 %S A096955 1195,1706489875,12184551018734375,24359780855939418203125, %T A096955 104359128170408663038552734375,1639301884061026141391921953564453125, %U A096955 30432532948821209122295591520605416259765625 %N A096955 Denominators of rational approximation to Pi/4 from Machins's formula. %C A096955 Machin's formula: Pi/4 = 4*arctan(1/5) - arctan(1/239). %C A096955 Numerators are given in A096954. %D A096955 W. Walter, Analysis I (in German), Springer, 3. Auflage, 1992; p. 216. %H A096955 Wolfdieter Lang, <a href="/A096954/a096954.txt">More comments</a>. %H A096955 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MachinsFormula.html">Machin's Formula</a>. %F A096955 a(n) = denominator(M(n)), with M(n)=4*arctan(1/5, n) - arctan(1/239, n) with arctan(x, n):=sum((((-1)^k)*x^(2k+1))/(2*k+1), k=0..n). %e A096955 A096954(7)/a(7) = %e A096955 170660807873601670198453967268421248219727522686104 /217292089321202035784330810406062747771759033203125 %e A096955 = 0.78539816339715... %Y A096955 Cf. A003881, A096954. %K A096955 nonn,frac,easy %O A096955 0,1 %A A096955 _Wolfdieter Lang_, Jul 23 2004