Alternatively, as n is even or odd: T(n-2, k) + T(n-1, k-1) = T(n, k), T(n-2, k) + T(n-1, k) = T(n, k)
T(n, k) = binomial(floor(n/2)+k, floor((n-1)/2-k) ). -
Paul Barry, Jun 22 2005
Beginning with the second polynomial in the example and offset=0, P(n,t)= Sum_{j=0..n}, binomial(n-j,j)*x^j with the convention that 1/k! is zero for k=-1,-2,..., i.e., 1/k! = lim_{c->0} 1/(k+c)!. -
Tom Copeland, Oct 11 2014
O.g.f.: (x + x^2 - x^3) / (1 - (2+t)*x^2 + x^4) = (x^2 (even part) + x*(1-x^2) (odd)) / (1 - (2+t)*x^2 + x^4).
Recursion relations:
A) p(n,t) = p(n-1,t) + p(n-2,t) for n=2,4,6,8,...
B) p(n,t) = t*p(n-1,t) + p(n-2,t) for n=3,5,7,...
C) a(n,k) = a(n-2,k) + a(n-1,k) for n=4,6,8,...
D) a(n,k) = a(n-2,k) + a(n-1,k-1) for n=3,5,7,...
Relation A generalized to MV(n,t;r) = P(2n+1,t) + r R(2n,t) for n=1,2,3,... (cf.
A078812 and
A085478) is the generating relation on p. 229 of Andre-Jeannine for the generalized Morgan-Voyce polynomials, e.g., MV(2,t;r) = p(5,t) + r*p(4,t) = (1 + 3t + t^2) + r*(2 + t) = (1 + 2r) + (3 + r)*t + t^2, so P(n,t) = MV(n-4,t;1) for n=4,6,8,... .
The even and odd polynomials are also presented in Trzaska and Ferri.
Dropping the initial 0 and re-indexing with initial m=0 gives the row polynomials Fb(m,t) = p(n+1,t) below with o.g.f. G(t,x)/x, starting with Fb(0,t) = 1, Fb(1,t) = 1, Fb(2,t) = 1 + t, and Fb(3,t) = 2 + t.
The o.g.f. x/G(x,t) = (1 - (2+t)*x^2 + x^4) / (1 + x - x^2) then generates a sequence of polynomials IFb(t) such that the convolution Sum_{k=0..n} IFb(n-k,t) Fb(k,t) vanishes for n>1 and is one for n=0. These linear polynomials have the basic Fibonacci numbers
A000045 as an overall factor:
IFb(0,t) = 1
IFb(1,t) = -1
IFb(2,t) = -t
IFb(3,t) = -1 (1-t)
IFb(4,t) = 2 (1-t)
IFb(5,t) = -3 (1-t)
IFb(6,t) = 5 (1-t)
IFb(7,t) = -8 (1-t)
IFb(8,t) = 13 (1-t)
... .
(End)
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