OFFSET
0,4
REFERENCES
N. Biggs, Algebraic Graph Theory, Cambridge, 2nd. Ed., 1993, p. 20.
F. Harary, Graph Theory, Addison-Wesley, 1969, p. 89.
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (2,5,-6).
FORMULA
G.f.: x*(1-2*x)/((1-x)*(1+2*x)*(1-3*x)).
a(n) = (3^(n+1) + (-2)^(n+3) + 5)/30.
E.g.f.: (3*exp(3*x) - 8*exp(-2*x) +5*exp(x))/30. - G. C. Greubel, Feb 01 2019
MATHEMATICA
Table[(3^(n+1)+(-2)^(n+3)+5)/30, {n, 0, 30}] (* or *) LinearRecurrence[{2, 5, -6}, {0, 1, 0}, 30] (* G. C. Greubel, Feb 01 2019 *)
PROG
(PARI) vector(30, n, n--; (3^(n+1)+(-2)^(n+3)+5)/30) \\ G. C. Greubel, Feb 01 2019
(Magma) [(3^(n+1)+(-2)^(n+3)+5)/30: n in [0..30]]; // G. C. Greubel, Feb 01 2019
(Sage) [(3^(n+1)+(-2)^(n+3)+5)/30 for n in (0..30)] # G. C. Greubel, Feb 01 2019
(GAP) List([0..30], n -> (3^(n+1)+(-2)^(n+3)+5)/30) # G. C. Greubel, Feb 01 2019
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Dec 12 2003
STATUS
approved