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 A155493 #7 Apr 01 2022 18:23:43 %S A155493 1,1,1,1,15,1,1,118,118,1,1,770,3540,770,1,1,4671,67810,67810,4671,1, %T A155493 1,27321,1039689,3085355,1039689,27321,1,1,156220,14006244,99524810, %U A155493 99524810,14006244,156220,1,1,878868,173788752,2602528824,6090918372,2602528824,173788752,878868,1 %N A155493 Triangle T(n, k) = binomial(n+1, k)*A142459(n+1, k+1)/(k+1), read by rows. %H A155493 G. C. Greubel, <a href="/A155493/b155493.txt">Rows n = 0..50 of the triangle, flattened</a> %F A155493 T(n, k) = binomial(n+1, k)*t(n, k, m)/(k+1), where t(n,k,m) = (m*(n-k)+1)*t(n-1,k-1,m) + (m*k-m+1)*t(n-1,k,m), t(n,1,m) = t(n,n,m) = 1, and m = 4. %F A155493 From _G. C. Greubel_, Apr 01 2022: (Start) %F A155493 T(n, k) = binomial(n+1, k)*A142459(n+1, k+1)/(k+1). %F A155493 T(n, n-k) = T(n, k). (End) %e A155493 Triangle begins as: %e A155493 1; %e A155493 1, 1; %e A155493 1, 15, 1; %e A155493 1, 118, 118, 1; %e A155493 1, 770, 3540, 770, 1; %e A155493 1, 4671, 67810, 67810, 4671, 1; %e A155493 1, 27321, 1039689, 3085355, 1039689, 27321, 1; %e A155493 1, 156220, 14006244, 99524810, 99524810, 14006244, 156220, 1; %e A155493 1, 878868, 173788752, 2602528824, 6090918372, 2602528824, 173788752, 878868, 1; %t A155493 t[n_, k_, m_]:= t[n,k,m]= If[k==1 || k==n, 1, (m*n-m*k+1)*t[n-1,k-1,m] + (m*k -(m -1))*t[n-1,k,m]]; %t A155493 T[n_, k_, m_]:= Binomial[n+1,k]*t[n+1,k+1,m]/(k+1); %t A155493 Table[T[n,k,4], {n,0,12}, {k,0,n}]//Flatten (* modified by _G. C. Greubel_, Apr 01 2022 *) %o A155493 (Sage) %o A155493 @CachedFunction %o A155493 def t(n,k,m): %o A155493 if (k==1 or k==n): return 1 %o A155493 else: return (m*(n-k)+1)*t(n-1,k-1,m) + (m*k-m+1)*t(n-1,k,m) %o A155493 def T(n,k,m): return binomial(n+1,k)*t(n+1,k+1,m)/(k+1) %o A155493 flatten([[T(n,k,4) for k in (0..n)] for n in (0..12)]) # _G. C. Greubel_, Apr 01 2022 %Y A155493 Cf. A001263 (m=0), A155467 (m=1), A155491 (m=3), this sequence (m=4). %Y A155493 Cf. A142459. %K A155493 nonn,tabl %O A155493 0,5 %A A155493 _Roger L. Bagula_, Jan 23 2009 %E A155493 Edited by _G. C. Greubel_, Apr 01 2022