OFFSET
0,3
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
H. Bruhn, L. Gellert, J. Günther, Jacobsthal numbers in generalised Petersen graphs, arXiv preprint arXiv:1503.03390 [math.CO], 2015.
H. Bruhn, L. Gellert, J. Günther, Jacobsthal numbers in generalised Petersen graphs, Electronic Notes in Discrete Math., 2015.
Index entries for linear recurrences with constant coefficients, signature (0,5,0,-4).
FORMULA
From Colin Barker, Apr 01 2016: (Start)
a(n) = (-3+3*(-2)^n-5*(-1)^n+5*2^n)/6.
a(n) = (2^(n+3)-8)/6 for n even.
a(n) = (2^(n+1)+2)/6 for n odd.
a(n) = 5*a(n-2)-4*a(n-4) for n>3.
G.f.: x*(1+4*x-2*x^2) / ((1-x)*(1+x)*(1-2*x)*(1+2*x)).
(End)
PROG
(PARI) concat(0, Vec(x*(1+4*x-2*x^2)/((1-x)*(1+x)*(1-2*x)*(1+2*x)) + O(x^50))) \\ Colin Barker, Apr 01 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Mar 31 2016
STATUS
approved