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 A344849 #15 Aug 10 2021 11:06:50
%S A344849 1,1,7,20,313,344,24634,86008,183349,3301264,132174038,69326344,
%T A344849 3332927794,17361255440,108222173516,406589577424,26070625295573,
%U A344849 8970328188896,55462481190898,1055714050810664,2169454884422962,91277283963562352,8046203518285051612,686567135431420560
%N A344849 a(n) is the numerator of Catalan-Daehee number d(n).
%H A344849 Dae San Kim and Taekyun Kim, <a href="https://doi.org/10.1134/S1061920817040057">A new approach to Catalan numbers using differential equations</a>, Russ. J. Math. Phys. 24, 465-475 (2017).
%H A344849 Taekyun Kim and Dae San Kim, <a href="https://www.researchgate.net/publication/349589625_SOME_IDENTITIES_OF_CATALAN-DAEHEE_POLYNOMIALS_ARISING_FROM_UMBRAL_CALCULUS">Some identities of Catalan-Daehee polynomials arising from umbral calculus</a>, Appl. Comput. Math. 16 (2017), no. 2, 177-189.
%H A344849 Yuankui Ma, Taekyun Kim, Dae San Kim and Hyunseok Lee, <a href="https://arxiv.org/abs/2105.12013">Study on q-analogues of Catalan-Daehee numbers and polynomials</a>, arXiv:2105.12013 [math.NT], 2021.
%F A344849 G.f. of d(n): log(1 - 4*x)/(2*(sqrt(1 - 4*x) - 1)).
%F A344849 a(n) = numerator(d(n)), where d(n) = 4^n/(n + 1) - Sum_{m=0..n-1} 4^(n-m-1)*C(m)/(n - m) with d(0) = 1 and C(m) is the m-th Catalan number.
%t A344849 nmax:=24; a[n_]:=Numerator[Coefficient[Series[Log[1-4x]/(2(Sqrt[1-4x]-1)),{x,0,nmax}],x,n]]; Array[a,nmax,0] (* or *)
%t A344849 a[n_]:=Numerator[If[n==0,1,4^n/(n+1)-Sum[4^(n-m-1)CatalanNumber[m]/(n-m),{m,0,n-1}]]]; Array[a,24,0]
%Y A344849 Cf. A000108, A000302, A014973 (denominators of Daehee numbers), A343206, A344850 (denominators).
%K A344849 nonn,frac
%O A344849 0,3
%A A344849 _Stefano Spezia_, May 30 2021