login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A203004 Array:  row n shows the coefficients of the characteristic polynomial of the n-th principal submatrix of the symmetric matrix A203003; by antidiagonals. 3
1, -1, 1, -18, 1, 1, -84, 116, -1, 1, -439, 1221, -839, 1, 1, -2475, 10435, -13855, 5658, -1, 1, -14312, 81690, -165715, 138669, -39038, 1, 1, -83270, 601411, -1661956, 2164099, -1292751, 266899, -1, 1, -485157 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Let p(n)=p(n,x) be the characteristic polynomial of the n-th principal submatrix. The zeros of p(n) are positive, and they interlace the zeros of p(n+1).

LINKS

Table of n, a(n) for n=1..37.

S.-G. Hwang, Cauchy's interlace theorem for eigenvalues of Hermitian matrices, American Mathematical Monthly 111 (2004) 157-159.

A. Mercer and P. Mercer, Cauchy's interlace theorem and lower bounds for the spectral radius, International Journal of Mathematics and Mathematical Sciences 23, no. 8 (2000) 563-566.

EXAMPLE

Top of the array:

1...-1

1...-18....1

1...-84....116....-1

1...-439...1221...-839...1

MATHEMATICA

f[k_] := Fibonacci[k + 1]^2;

U[n_] := NestList[Most[Prepend[#, 0]] &, #, Length[#] - 1] &[Table[f[k], {k, 1, n}]];

L[n_] := Transpose[U[n]];

F[n_] := CharacteristicPolynomial[L[n].U[n], x];

c[n_] := CoefficientList[F[n], x]

TableForm[Flatten[Table[F[n], {n, 1, 10}]]]

Table[c[n], {n, 1, 12}]

Flatten[%]

TableForm[Table[c[n], {n, 1, 10}]]

CROSSREFS

Cf. A203003, A202605.

Sequence in context: A174451 A144405 A202671 * A155497 A202677 A179838

Adjacent sequences:  A203001 A203002 A203003 * A203005 A203006 A203007

KEYWORD

tabl,sign

AUTHOR

Clark Kimberling, Dec 27 2011

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 22 13:47 EST 2019. Contains 329393 sequences. (Running on oeis4.)