OFFSET
0,1
COMMENTS
For n > 1, also the number of connected dominating sets in the n-Plummer-Toft graph.
LINKS
Eric Weisstein's World of Mathematics, Connected Dominating Set.
Eric Weisstein's World of Mathematics, Plummer-Toft Graph.
Index entries for linear recurrences with constant coefficients, signature (3,-2).
FORMULA
a(n) = 3*a(n-1)-2*a(n-2).
G.f.: (25-33*x)/(1-3*x+2*x^2).
E.g.f.: exp(x)*(8 + 17*exp(x)). - Stefano Spezia, Nov 20 2025
MATHEMATICA
Table[2 (4 + 17 2^(n - 1)), {n, 0, 20}]
LinearRecurrence[{3, -2}, {42, 76}, {0, 20}]
CoefficientList[Series[(25 - 33 x)/(1 - 3 x + 2 x^2), {x, 0, 20}], x]
PROG
(Python)
def A381791(n): return 8+(17<<n) # Chai Wah Wu, Mar 07 2025
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Mar 07 2025
STATUS
approved
