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 A095153 #27 Mar 18 2024 16:46:51
%S A095153 35,1225,24990,426650,6779185,104394675,1585021340,23909487700,
%T A095153 359582866335,5400330984125,81051093085690,1216089331752750,
%U A095153 18243600636165485,273669834496409575,4105158293128058040,61578149829707541800,923677675484159636635
%N A095153 Number of 4-block covers of a labeled n-set.
%H A095153 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (26,-196,486,-315).
%F A095153 a(n) = (1/4!)*(-50+35*3^n-10*7^n+15^n).
%F A095153 G.f.: 35*x^3*(9*x+1) / ((x-1)*(3*x-1)*(7*x-1)*(15*x-1)). - _Colin Barker_, Jul 13 2013
%F A095153 a(n) = Sum_{i=0..n} (-1)^i * C(n,i) * C(2^(n-i)-1,4). - _Geoffrey Critzer_, Aug 24 2014
%F A095153 a(n) = 26*a(n-1)-196*a(n-2)+486*a(n-3)-315*a(n-4). - _Wesley Ivan Hurt_, Aug 26 2014
%p A095153 A095153:=n->(-50+35*3^n-10*7^n+15^n)/24: seq(A095153(n), n=3..20); # _Wesley Ivan Hurt_, Aug 26 2014
%t A095153 nn = 19; Table[Sum[(-1)^i Binomial[n, i] Binomial[2^(n - i) - 1, 4], {i, 0, n}], {n, 3, nn}] (* _Geoffrey Critzer_, Aug 24 2014 *)
%t A095153 Table[(-50 + 35*3^n - 10*7^n + 15^n)/24, {n, 3, 20}] (* _Wesley Ivan Hurt_, Aug 26 2014 *)
%o A095153 (Magma) [(-50 + 35*3^n - 10*7^n + 15^n)/24 : n in [3..20]]; // _Wesley Ivan Hurt_, Aug 26 2014
%Y A095153 Column of A055154.
%K A095153 easy,nonn
%O A095153 3,1
%A A095153 _Vladeta Jovovic_, May 31 2004
%E A095153 More terms from _Colin Barker_, Jul 13 2013