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 A140873 #21 Apr 05 2021 00:06:16 %S A140873 -60,-240,-280,840,-1440,-1200,3360,5040,-6720,-4704,-15120,26880, %T A140873 26880,-26880,-17024,-60480,-110880,161280,129024,-96768,-57600, %U A140873 332640,-604800,-705600,806400,564480,-322560,-184320,1330560,2882880,-4435200,-3991680,3548160,2280960,-1013760,-563200 %N A140873 Triangle T(n, k) = H(n, k+1) - 2*H(n, k) - H(n, k-1), where H(n, k) = A060821(n+3, k), read by rows. %H A140873 G. C. Greubel, <a href="/A140873/b140873.txt">Rows n = 1..50 of the triangle, flattened</a> %F A140873 T(n, k) = H(n, k+1) - 2*H(n, k) - H(n, k-1), where H(n, k) = A060821(n+3, k). %e A140873 Triangle begins as: %e A140873 -60; %e A140873 -240, -280; %e A140873 840, -1440, -1200; %e A140873 3360, 5040, -6720, -4704; %e A140873 -15120, 26880, 26880, -26880, -17024; %e A140873 -60480, -110880, 161280, 129024, -96768, -57600; %e A140873 332640, -604800, -705600, 806400, 564480, -322560, -184320; %e A140873 1330560, 2882880, -4435200, -3991680, 3548160, 2280960, -1013760, -563200; %t A140873 A060821[n_, k_]:= If[EvenQ[n-k], (-1)^(Floor[(n-k)/2])*(2^k)*n!/(k!*(Floor[(n - k)/2]!)), 0]; %t A140873 T[n_, k_]:= A060821[n+3, k+1] -2*A060821[n+3, k] -A060821[n+3, k-1]; %t A140873 Table[T[n, k], {n, 15}, {k, n}]//Flatten (* corrected by _G. C. Greubel_, Dec 01 2020 *) %o A140873 (Sage) %o A140873 def A060821(n,k): return (-1)^((n-k)//2)*2^k*factorial(n)/(factorial(k)*factorial( (n-k)//2)) if (n-k)%2==0 else 0 %o A140873 def T(n,k): return A060821(n+3, k+1) -2*A060821(n+3, k) -A060821(n+3, k-1) %o A140873 flatten([[T(n,k) for k in (1..n)] for n in (1..15)]) # _G. C. Greubel_, Apr 04 2021 %Y A140873 Cf. A060821 (coefficients of Hermite polynomial). %K A140873 tabl,sign %O A140873 1,1 %A A140873 _Roger L. Bagula_ and _Gary W. Adamson_, Jul 21 2008 %E A140873 Name edited by _G. C. Greubel_, Dec 01 2020 %E A140873 Edited by _G. C. Greubel_, Apr 04 2021