A133084 A007318 * A133080.
1, 2, 1, 3, 2, 1, 4, 3, 4, 1, 5, 4, 10, 4, 1, 6, 5, 20, 10, 6, 1, 7, 6, 35, 20, 21, 6, 1, 8, 7, 56, 35, 56, 21, 8, 1, 9, 8, 84, 56, 126, 56, 36, 8, 1, 10, 9, 120, 84, 252, 126, 120, 36, 10, 1, 11, 10, 165, 120, 462, 252, 330, 120, 55, 10, 1
Offset: 1
Examples
First few rows of the triangle: 1; 2, 1; 3, 2, 1; 4, 3, 4, 1; 5, 4, 10, 4, 1; 6, 5, 20, 10, 6, 1; 7, 6, 35, 20, 21, 6, 1; ...
Links
- G. C. Greubel, Table of n, a(n) for the first 50 rows, flattened
Crossrefs
Programs
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Magma
/* As triangle */ [[(1-(1+(-1)^k)/2 )*Binomial(n, k)+((1+(-1)^k)/2)*Binomial(n-1, k-1): k in [1..n]]: n in [1.. 11]]; // Vincenzo Librandi, Oct 21 2017
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Maple
A133084 := proc(n,k) add(binomial(n-1,i-1)*A133080(i,k),i=1..n) ; end proc: # R. J. Mathar, Jun 13 2025
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Mathematica
u[1, x_] := 1; v[1, x_] := 1; z = 16; u[n_, x_] := u[n - 1, x] + x*v[n - 1, x]; v[n_, x_] := x*u[n - 1, x] + v[n - 1, x] + 1; Table[Expand[u[n, x]], {n, 1, z/2}] Table[Expand[v[n, x]], {n, 1, z/2}] cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; TableForm[cu] Flatten[%] (* A133567 *) Table[Expand[v[n, x]], {n, 1, z}] cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; TableForm[cv] Flatten[%] (* A133084 *) (* Clark Kimberling, Feb 28 2012 *) T[n_, k_] := If[k == n, 1, (1 - (1 + (-1)^k)/2 )*Binomial[n, k] + ((1 + (-1)^k)/2)*Binomial[n - 1, k - 1]]; Table[T[n, k], {n, 1, 10}, {k, 1, n}] (* G. C. Greubel, Oct 21 2017 *)
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PARI
for(n=1,10, for(k=1,n, print1(if(k == n, 1, (1 - (1 + (-1)^k)/2 )*binomial(n, k) + ((1 + (-1)^k)/2)*binomial(n - 1, k - 1)), ", "))) \\ G. C. Greubel, Oct 21 2017
Formula
Binomial transform of triangle A133080.
Comments