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 A299621 #9 Feb 16 2025 08:33:53 %S A299621 5,0,3,8,2,1,6,6,7,6,1,5,9,1,8,6,7,4,9,1,8,5,4,1,7,0,2,6,4,4,8,8,8,9, %T A299621 4,7,1,0,8,3,7,5,9,2,2,3,9,0,2,8,1,5,6,9,3,4,4,7,2,2,9,7,1,7,9,1,2,6, %U A299621 5,4,4,1,0,1,3,2,6,6,9,2,1,8,5,9,4,7 %N A299621 Decimal expansion of e^(W(1) + W(3)) = 3/(W(1)*W(3)), where W is the Lambert W function (or PowerLog); see Comments. %C A299621 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(3)) = 3/(W(1)*W(3)). See A299613 for a guide to related constants. %H A299621 G. C. Greubel, <a href="/A299621/b299621.txt">Table of n, a(n) for n = 1..10000</a> %H A299621 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LambertW-Function.html">Lambert W-Function</a> %e A299621 e^(W(1) + W(3)) = 5.03821667615918674918541702644888... %t A299621 w[x_] := ProductLog[x]; x = 1; y = 3; %t A299621 N[E^(w[x] + w[y]), 130] (* A299621 *) %t A299621 RealDigits[3/(LambertW[1]*LambertW[3]), 10, 100][[1]] (* _G. C. Greubel_, Mar 03 2018 *) %o A299621 (PARI) 3/(lambertw(1)*lambertw(3)) \\ _G. C. Greubel_, Mar 03 2018 %Y A299621 Cf. A299613, A299620. %K A299621 nonn,cons,easy %O A299621 1,1 %A A299621 _Clark Kimberling_, Mar 01 2018