OFFSET
0,2
LINKS
Rémy Sigrist, Table of n, a(n) for n = 0..1000
Reticular Chemistry Structure Resource (RCSR), The mcm tiling (or net)
Index entries for linear recurrences with constant coefficients, signature (3,-4,4,-3,1).
FORMULA
From Colin Barker, Dec 23 2017: (Start)
G.f.: (1 + x + 4*x^2 + 2*x^4 + x^5 - x^6) / ((1 - x)^3*(1 + x^2)).
a(n) = (-1/4-i/4)*((1-i) + (-i)^n - i*i^n) + 2*n + 2*n^2 for n>1, where i=sqrt(-1).
a(n) = 3*a(n-1) - 4*a(n-2) + 4*a(n-3) - 3*a(n-4) + a(n-5) for n>6.
(End)
PROG
(PARI) Vec((1 + x + 4*x^2 + 2*x^4 + x^5 - x^6) / ((1 - x)^3*(1 + x^2)) + O(x^50)) \\ Colin Barker, Dec 24 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Dec 22 2017
EXTENSIONS
Terms a(8)-a(20) and RCSR link from Davide M. Proserpio, Dec 22 2017
More terms from Rémy Sigrist, Dec 23 2017
STATUS
approved