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 A001361 #30 Feb 03 2022 02:30:19
%S A001361 1,241,26641,338401,2240161,10242001,36638641,109907521,288653761,
%T A001361 683158321,1486914001,3020862241,5793372001,10579330321,18522042481,
%U A001361 31261968001,51096647041,81176500081,125741512081,190404140641,282484116001,411401129041,589131731761
%N A001361 Number of points in interior of n-th crystal ball in E_8 lattice.
%H A001361 Vincenzo Librandi, <a href="/A001361/b001361.txt">Table of n, a(n) for n = 1..1000</a>
%H A001361 J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (<a href="http://neilsloane.com/doc/Me220.pdf">pdf</a>).
%H A001361 G. Nebe and N. J. A. Sloane, <a href="http://www.math.rwth-aachen.de/~Gabriele.Nebe/LATTICES/E8.html">Home page for this lattice</a>
%H A001361 <a href="/index/Cor#crystal_ball">Index entries for crystal ball sequences</a>
%H A001361 <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (9,-36,84,-126,126,-84,36,-9,1).
%F A001361 G.f.: -x*(x^8 + 232*x^7 + 7228*x^6 + 55384*x^5 + 133510*x^4 + 107224*x^3 + 24508*x^2 + 232*x + 1)/(x - 1)^9. - _Colin Barker_, Oct 29 2012
%p A001361 a:= n-> 57/7*n^8-108/7*n^7+30*n^6-72*n^5+39*n^4-36*n^3+300/7*n^2+24/7*n+1:
%p A001361 seq (a(n), n=1..30);
%t A001361 CoefficientList[Series[-(x^8 + 232 x^7 + 7228 x^6 + 55384 x^5 + 133510 x^4 + 107224 x^3 + 24508 x^2 + 232 x + 1)/(x - 1)^9, {x, 0, 40}], x] (* _Vincenzo Librandi_, Oct 13 2013 *)
%Y A001361 Cf. A008340, A008349.
%K A001361 nonn,easy
%O A001361 1,2
%A A001361 _N. J. A. Sloane_