OFFSET
0,2
COMMENTS
See a comment on V-V and V-S at A249246.
There are a total of 16 combinations as shown in the table below:
+-------------------------------------------------------+
| Even n-th version V-V S-V V-S S-S |
+-------------------------------------------------------+
| Odd n-th version |
+-------------------------------------------------------+
Note: V-V = vertex to vertex, S-V = side to vertex,
V-S = vertex to side, S-S = side to side.
LINKS
Kival Ngaokrajang, Illustration of initial terms
Index entries for linear recurrences with constant coefficients, signature (0,1,0,1,0,-1).
FORMULA
a(0) = 1, a(1) = 3; for even n >= 2, a(n) = 9*(n/2-1) + 3 or a(n) = A017197(n/2-1); for odd n >= 3, a(n) = a(n-2) + 9, if mod(n,4) = 1 otherwise a(n) = a(n-2) + 3.
Conjectures from Colin Barker, Sep 10 2015: (Start)
a(n) = a(n-2)+a(n-4)-a(n-6) for n>6.
G.f.: (7*x^6+6*x^5+8*x^4+3*x^3+2*x^2+3*x+1) / ((x-1)^2*(x+1)^2*(x^2+1)).
(End)
PROG
(PARI) a=3; print1("1, ", a, ", "); for (n=2, 100, if (Mod(n, 4)==0||Mod(n, 4)==2, print1(9*(n/2-1)+3, ", "), if (Mod(n, 4)==1, a=a+9, a=a+3); print1(a, ", ")))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Kival Ngaokrajang, Sep 06 2015
STATUS
approved