OFFSET
0,2
COMMENTS
Also the number of chordless cycles in 2n-crossed prism graph for n >= 3.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Eric Weisstein's World of Mathematics, Chordless Cycle.
Eric Weisstein's World of Mathematics, Crossed Prism Graph.
Index entries for linear recurrences with constant coefficients, signature (4,-5,2).
FORMULA
a(n) = 4*a(n-1) - 5*a(n-2) + 2*a(n-3).
G.f.: (-1 - 3*x + 9*x^2)/((-1 + x)^2*(-1 + 2*x)).
E.g.f.: exp(x)*(exp(x) + 5*x). - Elmo R. Oliveira, Aug 23 2024
MATHEMATICA
Table[5 n + 2^n, {n, 0, 20}]
LinearRecurrence[{4, -5, 2}, {7, 14, 23}, {0, 20}]
seq = CoefficientList[Series[(-1 - 3 x + 9 x^2)/((-1 + x)^2 (-1 + 2 x)), {x, 0, 20}], x]
PROG
(Magma) I:=[1, 7, 14]; [n le 3 select I[n] else 4*Self(n-1)- 5*Self(n-2)+2*Self(n-3): n in [1..40]]; // Vincenzo Librandi, Feb 21 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Jan 02 2018
STATUS
approved