Search: id:a209695
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A209695
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Triangle of coefficients of polynomials u(n,x) jointly generated with A209696; see the Formula section.
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+0
3
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1, 1, 2, 1, 5, 5, 1, 8, 18, 12, 1, 11, 40, 58, 29, 1, 14, 71, 164, 175, 70, 1, 17, 111, 357, 601, 507, 169, 1, 20, 160, 664, 1550, 2048, 1428, 408, 1, 23, 218, 1112, 3346, 6106, 6632, 3940, 985, 1, 26, 285, 1728, 6394, 15012, 22442, 20680, 10701, 2378
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OFFSET
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1,3
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COMMENTS
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Alternating row sums: 1,-1,1,-1,1,-1,1,-1,...
For a discussion and guide to related arrays, see A208510.
Subtriangle of the triangle given by (1, 0, 1/2, -1/2, 0, 0, 0, 0, 0, 0, ...) DELTA (0, 2, 1/2, -1/2, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938. - Philippe Deléham, Mar 24 2012
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LINKS
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FORMULA
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u(n,x) = x*u(n-1,x) + (x+1)*v(n-1,x),
v(n,x) = 2x*u(n-1,x) + (x+1)*v(n-1,x),
where u(1,x)=1, v(1,x)=1.
As DELTA-triangle T(n,k) with 0 <= k <= n:
G.f.: (1-2*y*x-y*x^2-y^2*x^2)/(1-x-2*y*x-y*x^2-y^2*x^2).
T(n,k) = T(n-1,k) + 2*T(n-1,k-1) + T(n-2,k-1) + T(n-2,k-2), T(0,0) = T(1,0) = T(2,0) = 1, T(1,1) = T(2,2) = 0, T(2,1) = 2 and T(n,k) = 0 if k < 0 or if k > n. (End)
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EXAMPLE
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First five rows:
1;
1, 2;
1, 5, 5;
1, 8, 18, 12;
1, 11, 40, 58, 29;
First three polynomials u(n,x):
1
1 + 2x
1 + 5x + 5x^2.
(1, 0, 1/2, -1/2, 0, 0, ...) DELTA (0, 2, 1/2, -1/2, 0, 0, ...) begins:
1;
1, 0;
1, 2, 0;
1, 5, 5, 0;
1, 8, 18, 12, 0;
1, 11, 40, 58, 29, 0; (End)
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MATHEMATICA
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u[1, x_] := 1; v[1, x_] := 1; z = 16;
u[n_, x_] := x*u[n - 1, x] + (x + 1)*v[n - 1, x];
v[n_, x_] := 2 x*u[n - 1, x] + (x + 1)*v[n - 1, x];
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]
Table[Expand[v[n, x]], {n, 1, z}]
cv = Table[CoefficientList[v[n, x], x], {n, 1, z}];
TableForm[cv]
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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