A226509 Expansion of (3-2*x)/(1-x-x^3)+x/(1-x)^2+x/(1-x^2).

3, 3, 3, 8, 9, 12, 16, 23, 29, 41, 56, 79, 110, 158, 225, 325, 469, 682, 991, 1446, 2110, 3085, 4511, 6603, 9666, 14157, 20736, 30380, 44511, 65223, 95575, 140060, 205253, 300800, 440828, 646051, 946817, 1387613, 2033628, 2980411

Offset: 0

Author

N. J. A. Sloane, Jun 11 2013

Keywords

• nonn
• easy

References

• Z. Skupien, Sums of Powered Characteristic Roots Count Distance-Independent Circular Sets, Discussiones Mathematicae Graph Theory. Volume 33, Issue 1, Pages 217-229, ISSN (Print) 2083-5892, DOI: 10.7151/dmgt.1658, April 2013.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (2,0,-1,0,-1,1).

Programs

Mathematica

CoefficientList[Series[(3 - 2 x) / (1 - x - x^3) + x / (1 - x)^2 + x / (1 - x^2), {x, 0, 40}], x] (* Vincenzo Librandi, Jun 19 2013 *)

Formula

a(n) = A137726(n), for n>2 and a(0) = a(1) = a(2) = 3. [Bruno Berselli, Jun 17 2013]