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 A178693 #16 Sep 08 2022 08:45:54
%S A178693 1,1,5,5,45,95,465,1165,24445,65595,359915,1003315,11342185,32415435,
%T A178693 187063145,544172445,25508284445,75196195795,445774614215,
%U A178693 1327748661015,15887874844835,47715177777185,287618252461095,869652752181595
%N A178693 Numerators of coefficients of Maclaurin series for 2 - sqrt(1 - x - x^2).
%C A178693 Every term after the second is a multiple of 5.
%D A178693 M. Kauers and P. Paule, The Concrete Tetrahedron, Springer 2011, p. 41.
%H A178693 G. C. Greubel, <a href="/A178693/b178693.txt">Table of n, a(n) for n = 0..1000</a>
%F A178693 G.f.: 2 - sqrt(1 - x - x^2) for the fractions (not the numerators).
%e A178693 The Maclaurin series begins with 1 + (1/2)*x + (5/8)*x^2 + (5/16)*x^3 + ....
%t A178693 Numerator[CoefficientList[Series[2-Sqrt[1-x-x^2], {x, 0, 30}], x]] (* _G. C. Greubel_, Jan 25 2019 *)
%o A178693 (PARI) my(x='x+O('x^30)); v=Vec( 2-sqrt(1-x-x^2) ); vector(#v, n, numerator(v[n])) \\ _G. C. Greubel_, Jan 25 2019
%o A178693 (Magma) m:=30; R<x>:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!( 2-Sqrt(1-x-x^2) )); [Numerator(Factorial(n-1)*b[n]): n in [1..m]]; // _G. C. Greubel_, Jan 25 2019
%Y A178693 Cf. A178694.
%Y A178693 Cf. A046161 (denominators).
%K A178693 nonn,frac
%O A178693 0,3
%A A178693 _Clark Kimberling_, Jun 04 2010