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 A340819 #9 Jan 28 2021 03:35:28 %S A340819 6,9,54,4,264,308,7854,374,1564,11339,362848,127541072,1307295988, %T A340819 2614591976,42742894912,1132686715168,4608863185856,71437379380768, %U A340819 162734350229389504,46216555465146619136,427503138052606227008,270181983249247135469056,64347502466822129824768 %N A340819 Denominators of a sequence of fractions converging to A340820, the asymptotic density of numbers whose excess of prime divisors (A046660) is even (A162644). %C A340819 See A340818 for details. %H A340819 Amiram Eldar, <a href="/A340819/b340819.txt">Table of n, a(n) for n = 1..462</a> %t A340819 d[p_] := 1/(p*(p + 1)); delta[n_] := delta[n] = d[Prime[n]]; f[0] = 1; f[n_] := f[n] = f[n - 1] * (1 - delta[n]) + (1 - f[n - 1]) * delta[n]; Denominator @ Array[f, 30] %Y A340819 Cf. A046660, A162644, A340818 (numerators), A340820. %K A340819 nonn,frac %O A340819 1,1 %A A340819 _Amiram Eldar_, Jan 22 2021