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 A293258 #11 Nov 16 2021 07:19:59 %S A293258 9,2,1,8,9,3,8,3,5,2,9,6,9,3,1,8,5,9,1,9,4,6,7,0,3,0,2,7,9,9,8,0,7,1, %T A293258 8,6,7,3,2,2,0,5,4,7,8,7,3,8,8,6,2,6,7,4,9,7,6,2,3,0,6,6,0,3,9,3,8,6, %U A293258 4,4,5,3,1,2,2,8,6,0,8,9,3,7,0,9,3,8,7,5,6,0,5,5,6,0,8,5,5,3,9,4,8,7,0,2,6 %N A293258 Decimal expansion of product of 1 - 4^-p over all primes p. %C A293258 Knopfmacher proves that prime(n+1) = floor(1 - log(1 - A/P)) where A is this constant and P is the product (1 - 4^-2)(1 - 4^-3)(1 - 4^-5)...(1 - 4^-prime(n)). %H A293258 John Knopfmacher, <a href="https://doi.org/10.1007/BF01222738">Recursive formulae for prime numbers</a>, Archiv der Mathematik (Basel) 33:2 (1979/80), pp. 144-149. %F A293258 Equals A184082 * A184083 = A184082 / A184084. - _Amiram Eldar_, Nov 16 2021 %e A293258 0.921893835296931859194670302799807186732205478738862674976230660393864453122... %o A293258 (PARI) prodeuler(p=2, bitprecision(1.)/2+2, 1-4.^-p) %Y A293258 Cf. A184082, A184083, A184084. %K A293258 nonn,cons %O A293258 0,1 %A A293258 _Charles R Greathouse IV_, Oct 04 2017