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A099461 An Alexander sequence for the knot 9_48. 2
1, 7, 38, 196, 1001, 5110, 26093, 133252, 680510, 3475339, 17748434, 90640627, 462898478, 2364006148, 12072895733, 61655851222, 314874250049, 1608051650884, 8212262868470, 41939735818687, 214184746483778, 1093833919809295, 5586171115205846, 28528378178106436, 145693417671662033, 744051127629095062, 3799842775146922277, 19405662567631938052, 99104031922539424718 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The denominator 1-7x+11x^2-7x^3+x^4 is a parameterization of the Alexander polynomial for the knot 9_48. 1/(1-7*x+11*x^2-7*x^3+x^4) is the image of the g.f. of A099459 under the modified Chebyshev transform A(x)->(1/(1+x^2)^2)*A(x/(1+x^2)).

LINKS

Table of n, a(n) for n=0..28.

Dror Bar-Natan, The Rolfsen Knot Table

Index entries for linear recurrences with constant coefficients, signature (7,-11,7,-1).

FORMULA

a(n) = A099460(n) - A099460(n-2).

G.f.: (1-x)*(1+x)*(1+x^2)/(1-7*x+11*x^2-7*x^3+x^4). - Corrected by R. J. Mathar, Nov 23 2012

CROSSREFS

Sequence in context: A014827 A141845 A048437 * A104553 A027241 A292761

Adjacent sequences:  A099458 A099459 A099460 * A099462 A099463 A099464

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Oct 16 2004

STATUS

approved

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Last modified December 7 20:44 EST 2019. Contains 329849 sequences. (Running on oeis4.)