A230001 Triangular array read by rows: row n shows the coefficients of the polynomial v(n) = d(0) + d(1)*x + ... + d(k)*x^k which is the denominator of the n-th convergent of the continued fraction [1, 1/x, 1/x^2, ... ,1/x^n].

1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 0, 2, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 2, 0, 2, 0, 2, 0, 1, 1, 1, 1, 0, 1

Offset

0,53

Comments

In the Name section, k = n(n+1)/2 if n is even, and k = (n-1)(n+2)/2 if n is odd. For the numerator polynomials, see A230000. Conjecture: every nonnegative integer occurs infinitely many times.

Links

Table of n, a(n) for n=0..85.

Formula

Write the numerator polynomials as u(0), u(1), u(2), ... and the denominator polynomials as v(0), v(1), v(2),... Let p(0) = 1, q(0) = 1; p(1) = (1 + x)/x; q(1) = 1/x; p(n ) = p(n-1)/x^n + p(n-2), q(n) = q(n-1)/x^n + q(n-2). Then u(n)/v(n) = p(n)/q(n) for n>=0.

Example

The first 7 rows:
1 . . . . . . . . . . . . polynomial v(0) = 1
1 . . . . . . . . . . . . polynomial v(1) = 1
1 0 0 1 . . . . . . . . . v(2) = 1 + x^3
1 0 0 1 0 1 . . . . . . . v(3) = 1 + x^3 + x^5
1 0 0 1 0 1 0 1 0 0 1
1 0 0 1 0 1 0 1 0 1 1 0 1 0 1

Mathematica

t[n_] := t[n] = Table[1/x^k, {k, 0, n}];
b = Table[Factor[Denominator[t[n]]], {n, 0, 10}];
p[x_, n_] := p[x, n] = Last[Expand[Numerator[b]]][[n]];
u = Table[p[x, n], {n, 1, 10}]
v = CoefficientList[u, x]
Flatten[v]

Crossrefs

Cf. A230000.

Sequence in context: A035203 A357905 A173920 * A070100 A070095 A060951

Adjacent sequences: A229998 A229999 A230000 * A230002 A230003 A230004

Keyword

nonn,tabf

Author

Clark Kimberling, Oct 11 2013

Status

approved