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 A299615 #15 Nov 24 2024 08:24:59 %S A299615 1,4,1,9,7,4,8,7,9,2,4,2,3,5,0,9,3,6,4,3,4,6,4,4,1,0,7,6,9,0,5,6,7,3, %T A299615 0,1,6,6,5,2,2,6,9,0,8,7,3,3,7,9,1,6,0,1,6,9,0,7,2,3,8,4,7,3,8,7,5,5, %U A299615 6,0,8,5,8,7,6,0,9,4,7,6,1,1,5,8,9,7 %N A299615 Decimal expansion of W(1) + W(2), where w is the Lambert W function (or PowerLog); see Comments. %C A299615 The Lambert W function satisfies the functional equations W(x) + W(y) = W(x*y*(1/W(x) + 1/W(y))) = log(x*y)/(W(x)*W(y)) for x and y greater than -1/e, so that W(1) + W(2) = W(2/W(1) + 2/W(2)) = log(2) - log(W(1)) - log(W(2)). See A299613 for a guide to related sequences. %H A299615 G. C. Greubel, <a href="/A299615/b299615.txt">Table of n, a(n) for n = 1..10000</a> %H A299615 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LambertW-Function.html">Lambert W-Function</a>. %e A299615 W(1) + W(2) = 1.41974879242350936434644... %t A299615 w[x_] := ProductLog[x]; x = 1; y = 2; u = N[w[x] + w[y], 100] %t A299615 RealDigits[u, 10][[1]] (* A299615 *) %t A299615 RealDigits[LambertW[1] + LambertW[2], 10, 100][[1]] (* _G. C. Greubel_, Mar 03 2018 *) %o A299615 (PARI) lambertw(1) + lambertw(2) \\ _G. C. Greubel_, Mar 03 2018 %Y A299615 Cf. A299613, A299616. %K A299615 nonn,cons,easy %O A299615 1,2 %A A299615 _Clark Kimberling_, Mar 01 2018