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 A008991 #33 Feb 16 2025 08:32:32
%S A008991 1,-1,1,-1,-67,-1,-64397,-113249,-3679787,-810304169,-6040635661561,
%T A008991 -428305999661,-16827172241810597,-5620292762592913,
%U A008991 -1550760014054450957,-4168373361283100017,-8551022502876237590534947
%N A008991 Numerators of coefficients in expansion of sqrt(sin(x)/x) (even powers only).
%H A008991 G. C. Greubel, <a href="/A008991/b008991.txt">Table of n, a(n) for n = 0..255</a>
%H A008991 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SincFunction.html">The Sinc Function</a>.
%F A008991 sum(n>=0, A008991(n)/A008992(n) ) = A117017 - _Johannes W. Meijer_, Feb 10 2013
%p A008991 A008991 := n -> numer(coeff(taylor(sqrt(sin(x)/x), x, 2*n+2), x, 2*n)): seq(A008991(n), n=0..16); # _Johannes W. Meijer_, Feb 10 2013
%t A008991 Numerator[CoefficientList[Series[Sqrt[Sin[x]/x], {x, 0, 50}], x][[1 ;; -1 ;; 2]]] (* _G. C. Greubel_, Jul 21 2018 *)
%o A008991 (Sage)
%o A008991 length = 16; T = taylor(sqrt(sin(x)/x),x,0,2*length+2)
%o A008991 [T.coefficient(x, 2*n).numerator() for n in (0..length)]
%o A008991 # _Peter Luschny_, Dec 13 2012
%Y A008991 Denominators are in A008992.
%Y A008991 Appears in A220002 and A220466.
%K A008991 sign
%O A008991 0,5
%A A008991 _N. J. A. Sloane_