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 A006453 #13 Dec 26 2021 21:33:09 %S A006453 1,6,107,3186,132849,7122870,466788195,36153055890,3230902408545, %T A006453 327238250094630,37043457415695675,4634751809368192050, %U A006453 635113491345511326225,94599619441277679278550 %N A006453 Expansion of 1/sqrt(1 - 12x + x^2). %H A006453 J. Shallit, <a href="/A006449/a006449.pdf">Letter to N. J. A. Sloane, Oct. 1975</a> %F A006453 D-finite with recurrence: a(n) + 6*(-2*n+1)*a(n-1) + (n-1)^2*a(n-2) = 0. - _R. J. Mathar_, Jan 17 2020 %K A006453 nonn %O A006453 0,2 %A A006453 _N. J. A. Sloane_