login
A209694
Triangle of coefficients of polynomials v(n,x) jointly generated with A209693; see the Formula section.
3
1, 3, 1, 4, 6, 1, 5, 13, 10, 1, 6, 22, 32, 15, 1, 7, 33, 71, 66, 21, 1, 8, 46, 131, 186, 121, 28, 1, 9, 61, 216, 415, 422, 204, 36, 1, 10, 78, 330, 801, 1121, 862, 323, 45, 1, 11, 97, 477, 1400, 2507, 2689, 1625, 487, 55, 1, 12, 118, 661, 2276, 4977, 6902
OFFSET
1,2
COMMENTS
Alternating row sums are periodic. For a discussion and guide to related arrays, see A208510.
FORMULA
u(n,x)=x*u(n-1,x)+x*v(n-1,x),
v(n,x)=u(n-1,x)+(x+1)*v(n-1,x)+1,
where u(1,x)=1, v(1,x)=1.
EXAMPLE
First five rows:
1
3...1
4...6....1
5...13...10...1
6...22...32...15...1
First three polynomials v(n,x): 1, 3 + x , 4 + 6x + x^2.
MATHEMATICA
u[1, x_] := 1; v[1, x_] := 1; z = 16;
u[n_, x_] := x*u[n - 1, x] + x*v[n - 1, x];
v[n_, x_] := u[n - 1, x] + (x + 1)*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[%] (* A209693 *)
Table[Expand[v[n, x]], {n, 1, z}]
cv = Table[CoefficientList[v[n, x], x], {n, 1, z}];
TableForm[cv]
Flatten[%] (* A209694 *)
CROSSREFS
Sequence in context: A209518 A108285 A207619 * A286951 A260355 A075419
KEYWORD
nonn,tabl
AUTHOR
Clark Kimberling, Mar 12 2012
STATUS
approved