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 A065472 #33 May 28 2023 08:46:54
%S A065472 7,7,5,8,8,3,5,1,0,0,0,3,8,9,5,4,9,9,6,2,0,4,0,4,2,8,4,4,2,7,9,0,0,6,
%T A065472 1,1,4,8,2,4,1,3,4,6,5,9,7,3,0,1,6,2,7,6,2,2,1,0,6,3,1,1,6,4,6,1,3,8,
%U A065472 7,6,4,9,2,4,9,7,4,5,6,9,9,5,3,7,1,9,3,1,3,2,3,3,1,2,8,1,4,2
%N A065472 Decimal expansion of Product_{p prime} (1 - 1/(p+1)^2).
%C A065472 The probablity that two randomly chosen squarefree numbers are coprime. - _Amiram Eldar_, Aug 04 2020
%C A065472 The asymptotic mean of A001157(n)/(n*A000203(n)). - _Richard R. Forberg_, May 27 2023
%H A065472 G. Niklasch, <a href="/A001692/a001692.html">Some number theoretical constants: 1000-digit values</a>. [Cached copy]
%H A065472 László Tóth, <a href="https://www.raco.cat/index.php/CollectaneaMathematica/article/view/56858">The unitary analogue of Pillai's arithmetical function</a>, Collectanea Mathematica, Vol. 40, No. 1 (1989), pp. 19-30.
%F A065472 Equals lim_{n->oo} (Pi^2/(3*n^2*log(n))) * Sum_{k=1..n} A145388(k). - _Amiram Eldar_, May 14 2019
%F A065472 Equals Sum_{k>=1} mu(k)/sigma(k)^2, where mu is the Möbius function (A008683) and sigma(k) is the sum of divisors of k (A000203). - _Amiram Eldar_, Jan 14 2022
%e A065472 0.7758835100038954996204042844279...
%t A065472 digits = 98; Exp[NSum[(-1)^n*(2^(n-1)-2)*PrimeZetaP[n-1]/(n-1), {n, 3, Infinity}, WorkingPrecision -> 2 digits, Method -> "AlternatingSigns"]] // RealDigits[#, 10, digits]& // First (* _Jean-François Alcover_, Apr 18 2016 *)
%o A065472 (PARI) prodeulerrat(1 - 1/(p+1)^2) \\ _Amiram Eldar_, Mar 17 2021
%Y A065472 Cf. A000203, A001157, A008683, A038063, A078091, A116393, A145388.
%K A065472 cons,nonn
%O A065472 0,1
%A A065472 _N. J. A. Sloane_, Nov 19 2001
%E A065472 Definition corrected by Dan Asimov, Apr 15 2006