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 A140712 #21 Sep 30 2024 02:14:32
%S A140712 0,1,6,37,256,2000,17520,170520,1827840,21409920,272160000,3732220800,
%T A140712 54925516800,863480217600,14442536908800,256086230400000,
%U A140712 4798293147648000,94731418349568000,1965528727658496000
%N A140712 Number of white corners in all permutations of {1,2,...,n} (for definition see the Eriksson-Linusson references).
%D A140712 K. Eriksson and S. Linusson. Combinatorics of Fulton's essential set. Duke Mathematical Journal 85(1):61-76, 1996.
%H A140712 G. C. Greubel, <a href="/A140712/b140712.txt">Table of n, a(n) for n = 1..445</a>
%H A140712 K. Eriksson and S. Linusson, <a href="https://doi.org/10.37236/1200">The size of Fulton's essential set</a>, Electronic J. Combinatorics, Vol. 2, #R6, 1995.
%H A140712 K. Eriksson and S. Linusson, <a href="https://www.researchgate.net/publication/2550835_Combinatorics_of_Fulton's_essential_set">Combinatorics of Fulton's essential set</a>, ResearchGate, 1998.
%F A140712 a(n) = Sum_{k=0..n-1} k*A140711(n,k).
%F A140712 a(n) = (n-1)!*(binomial(n-1,3)+6*binomial(n,2))/6 = (n-1)!*(n-1)*(n^2+13*n+6)/36.
%F A140712 E.g.f.: (x*(6 + 3*x - 7*x^2) + (6 - 18*x + 18*x^2 - 6*x^3)*log(1-x))/(36* (1-x)^3). - _G. C. Greubel_, Nov 28 2018
%F A140712 D-finite with recurrence 2*(-n+5)*a(n) +(2*n^2-31*n+51)*a(n-1) +(25*n-14)*(n-2)*a(n-2)=0. - _R. J. Mathar_, Jul 26 2022
%p A140712 seq((1/36)*(n-1)*factorial(n-1)*(n^2+13*n+6),n=1..20);
%t A140712 Table[(n-1)!*(n-1)*(n^2 +13*n+6)/36, {n,1,20}] (* _G. C. Greubel_, Nov 28 2018 *)
%o A140712 (PARI) a(n)=(n^2+13*n+6)*(n-1)*(n-1)!/36 \\ _Charles R Greathouse IV_, Oct 31 2011
%o A140712 (Magma) [Factorial(n-1)*(n-1)*(n^2+13*n+6)/36: n in [1..20]]; // _G. C. Greubel_, Nov 28 2018
%o A140712 (Sage) [factorial(n-1)*(n-1)*(n^2 +13*n+6)/36 for n in (1..20)] # _G. C. Greubel_, Nov 28 2018
%o A140712 (GAP) List([1..30], n -> Factorial(n-1)*(n-1)*(n^2 +13*n+6)/36); # _G. C. Greubel_, Nov 28 2018
%Y A140712 Cf. A000142, A140711.
%K A140712 nonn,easy
%O A140712 1,3
%A A140712 _Emeric Deutsch_, May 28 2008