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A185904 Multiplication table for the tetrahedral numbers (A000292), by antidiagonals. 4

%I

%S 1,4,4,10,16,10,20,40,40,20,35,80,100,80,35,56,140,200,200,140,56,84,

%T 224,350,400,350,224,84,120,336,560,700,700,560,336,120,165,480,840,

%U 1120,1225,1120,840,480,165,220,660,1200,1680,1960,1960,1680,1200,660,220,286,880,1650,2400,2940,3136,2940,2400,1650,880,286,364,1144,2200,3300,4200,4704,4704,4200,3300,2200,1144,364,455,1456,2860,4400,5775,6720,7056,6720,5775,4400,2860,1456,455,560,1820,3640,5720,7700,9240,10080,10080,9240,7700,5720,3640,1820,560

%N Multiplication table for the tetrahedral numbers (A000292), by antidiagonals.

%C A member of the accumulation chain ... < A185906 < A000007 < A003991 < A098358 < A185904 < A185905 < ... (See A144112 for the definition of accumulation array.)

%H G. C. Greubel, <a href="/A185904/b185904.txt">Table of n, a(n) for the first 50 rows, flattened</a>

%F T(n,k) = binomial(k+2,3)*binomial(n+2,3), k >= 1, n >= 1.

%e Northwest corner:

%e 1, 4, 10, 20, 35

%e 4, 16, 40, 80, 140

%e 10, 40, 100, 200, 350

%e 20, 80, 200, 400, 700

%t (* This program generates A098358 and its accumulation array, A185904. *)

%t TableForm[Table[f[n,k],{n,1,10},{k,1,15}]] (* A098358 *)

%t Table[f[n-k+1,k],{n,14},{k,n,1,-1}]//Flatten

%t s[n_,k_]:=Sum[f[i,j],{i,1,n},{j,1,k}]; (* accumulation array of {f(n,k)} *)

%t FullSimplify[s[n,k]] (* formula for A185904 *)

%t TableForm[Table[s[n,k],{n,1,10},{k,1,15}]] (* A185904 *)

%t Table[s[n-k+1,k],{n,14},{k,n,1,-1}]//Flatten

%t T[n_, k_] := Binomial[k + 2, 3]*Binomial[n + 2, 3]; Table[T[n - k + 1, k], {n, 10}, {k, n, 1, -1}] // Flatten (* _G. C. Greubel_, Jul 22 2017 *)

%Y Cf. A000007, A003991, A098358, A144112, A185905, A185906, A185907.

%Y Row 1 = Column 1 = A000292.

%K nonn,tabl

%O 1,2

%A _Clark Kimberling_, Feb 06 2011

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Last modified May 10 03:11 EDT 2021. Contains 343747 sequences. (Running on oeis4.)