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 A034904 #27 Aug 18 2025 02:24:37
%S A034904 1,28,980,37730,1531838,64337196,2766499428,121034349975,
%T A034904 5365856182225,240390356963680,10861273400995360,494187939745288880,
%U A034904 22618601857572837200,1040455685448350511200,48069052667713793617440,2229202317465227179008780,103723472536176158740937940
%N A034904 Related to sept-factorial numbers A045754.
%C A034904 Convolution of A034835(n-1) with A025752(n), n >= 1.
%H A034904 Michael De Vlieger, <a href="/A034904/b034904.txt">Table of n, a(n) for n = 1..594</a>
%H A034904 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 A034904 <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a>.
%F A034904 a(n) = 7^(n-1)*A045754(n)/n!, where A045754(n) = (7*n-6)(!^7) = Product_{j=1..n} (7*j-6).
%F A034904 G.f.: (-1+(1-49*x)^(-1/7))/7.
%F A034904 D-finite with recurrence: n*a(n) + 7*(-7*n+6)*a(n-1) = 0. - _R. J. Mathar_, Jan 28 2020
%F A034904 a(n) ~ 7^(2*n-1) * n^(-6/7) / Gamma(1/7). - _Amiram Eldar_, Aug 18 2025
%t A034904 CoefficientList[Series[(Power[1-49x, (-7)^-1]-1)/7,{x,0,30}],x] (* _Harvey P. Dale_, Aug 23 2011 *)
%Y A034904 Cf. A025752, A034835, A045754, A220086.
%K A034904 easy,nonn
%O A034904 1,2
%A A034904 _Wolfdieter Lang_