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 A034255 #25 Aug 18 2025 02:24:22
%S A034255 1,10,120,1560,21216,297024,4243200,61526400,902387200,13355330560,
%T A034255 199115837440,2986737561600,45030812467200,681895160217600,
%U A034255 10364806435307520,158063298138439680,2417438677411430400,37067393053641932800,569667303771760230400,8772876478085107548160
%N A034255 Related to quartic factorial numbers A007696.
%H A034255 Michael De Vlieger, <a href="/A034255/b034255.txt">Table of n, a(n) for n = 1..833</a>
%H A034255 Wolfdieter Lang, <a href="http://www.cs.uwaterloo.ca/journals/JIS/index.html">On generalizations of Stirling number triangles</a>, J. Integer Seq., Vol. 3 (2000), Article 00.2.4.
%H A034255 Elżbieta Liszewska and Wojciech Młotkowski, <a href="https://arxiv.org/abs/1907.10725">Some relatives of the Catalan sequence</a>, arXiv:1907.10725 [math.CO], 2019.
%H A034255 <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a>.
%F A034255 a(n) = 4^(n-1)*A007696(n)/n!, where A007696(n) = (4*n-3)(!^4) = Product_{j=1..n} (4*j-3), n >= 1.
%F A034255 G.f.: (-1+(1-16*x)^(-1/4))/4.
%F A034255 a(n) = A048882(n, 1).
%F A034255 Convolution of A034385(n-1) with A025749(n), n >= 1.
%F A034255 D-finite with recurrence: n*a(n) + 4*(-4*n+3)*a(n-1) = 0. - _R. J. Mathar_, Jan 28 2020
%F A034255 a(n) ~ 2^(4*n-2) * n^(-3/4) / Gamma(1/4). - _Amiram Eldar_, Aug 18 2025
%t A034255 Rest[CoefficientList[Series[(-1+(1-16x)^(-1/4))/4,{x,0,20}],x]] (* _Harvey P. Dale_, May 19 2011 *)
%Y A034255 First column of triangle A048882.
%Y A034255 Cf. A007696, A068466.
%K A034255 easy,nonn
%O A034255 1,2
%A A034255 _Wolfdieter Lang_