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 A299619 #9 Feb 16 2025 08:33:53 %S A299619 2,3,2,9,3,9,3,2,6,6,8,4,2,7,9,3,2,2,4,8,5,7,6,3,0,9,1,5,6,2,7,5,2,1, %T A299619 9,4,3,5,7,7,4,3,9,1,9,8,0,2,3,3,3,1,5,1,3,4,6,7,1,4,9,2,5,2,4,7,2,6, %U A299619 0,2,7,8,6,1,6,3,1,0,9,1,0,5,1,1,6,6 %N A299619 Decimal expansion of e^(W(1) + W(1/e)) = (1/e)/(W(1)*W(1/e)), where W is the Lambert W function (or PowerLog); see Comments. %C A299619 The Lambert W function satisfies the functional equation e^(W(x) + W(y)) = x*y/(W(x)*W(y)) for x and y greater than -1/e, so that e^(W(1) + W(1/e)) = (1/e)/(W(1)*W(1/e)). See A299613 for a guide to related constants. %H A299619 G. C. Greubel, <a href="/A299619/b299619.txt">Table of n, a(n) for n = 1..10000</a> %H A299619 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LambertW-Function.html">Lambert W-Function</a> %e A299619 e^(W(1) + W(1/e)) = 2.3293932668427932248576309... %t A299619 w[x_] := ProductLog[x]; x = 1; y = 1/E; %t A299619 N[E^(w[x] + w[y]), 130] (* A299619 *) %t A299619 RealDigits[1/(E*LambertW[1]*LambertW[1/E]), 10, 100][[1]] (* _G. C. Greubel_, Mar 03 2018 *) %o A299619 (PARI) exp(-1)/(lambertw(1)*lambertw(exp(-1))) \\ _G. C. Greubel_, Mar 03 2018 %Y A299619 Cf. A299613, A299618. %K A299619 nonn,cons,easy %O A299619 1,1 %A A299619 _Clark Kimberling_, Mar 01 2018