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 A346441 #29 Feb 23 2024 02:15:19
%S A346441 8,3,4,7,1,9,4,6,8,5,7,7,2,1,0,9,6,2,2,1,9,2,8,3,2,3,9,2,0,8,3,3,0,0,
%T A346441 7,0,8,4,0,3,7,9,0,5,1,9,9,8,2,6,9,7,6,7,6,2,7,6,9,5,1,0,7,9,5,2,5,9,
%U A346441 2,7,8,4,3,6,8,7,2,2,2,2,3,8,9,7,3,0,0
%N A346441 Decimal expansion of the constant Sum_{k>=0} (-1)^k/(3*k)!.
%H A346441 Peter Bala, <a href="/A346441/a346441.pdf">A continued fraction for A346441</a>
%H A346441 D. Bowman and J. Mc Laughlin, <a href="https://doi.org/10.4064/aa103-4-3">Polynomial continued fractions</a>, Acta Arith. 103 (2002), no. 4, 329-342.
%H A346441 Michael I. Shamos, <a href="http://euro.ecom.cmu.edu/people/faculty/mshamos/cat.pdf">A catalog of the real numbers</a> (2011).
%F A346441 Equals 1/(3*e) + 2*sqrt(e)*cos(sqrt(3)/2)/3. - _Amiram Eldar_, Jul 18 2021
%F A346441 Continued fraction: 1/(1 + 1/(5 + 6/(119 + 120/(503 + ... + P(n-1)/((P(n) - 1) + ... ))))), where P(n) = (3*n)*(3*n - 1)*(3*n - 2) for n >= 1. See Bowman and Mc Laughlin, Corollary 10, p. 341 with m = 1, who also show that the constant is irrational. - _Peter Bala_, Feb 21 2024
%e A346441 0.8347194685772109622192832392...
%t A346441 RealDigits[Sum[(-1)^k/(3*k)!, {k, 0, Infinity}], 10, 100][[1]] (* _Amiram Eldar_, Jul 18 2021 *)
%o A346441 (PARI) sumalt(k=0, (-1)^k/(3*k)!) \\ _Michel Marcus_, Jul 18 2021
%Y A346441 Cf. A068985, A049470, A143819, A346440, A346439, A346438, A346437, A346436, A346435, A196498.
%K A346441 nonn,cons
%O A346441 0,1
%A A346441 _Sean A. Irvine_, Jul 17 2021