OFFSET
0,3
COMMENTS
The pattern is generated by adding subdiagonals parallel to principal diagonals at a spacing of at least 1 box in any direction from the previous generation.
Conjectures:
(i) a(n) is the total number of boxes (or 1's) at the n-th iteration.
(ii) The total number of left boxes (or 0's) is 4*A056827.
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Kival Ngaokrajang, Illustration of initial terms
Index entries for linear recurrences with constant coefficients, signature (2,-1,0,0,0,1,-2,1).
FORMULA
a(n) = n^2 - 4*floor(n^2/6) for n >= 0.
From Colin Barker, Jan 16 2016: (Start)
a(n) = 2*a(n-1) - a(n-2) + a(n-6) - 2*a(n-7) + a(n-8) for n>7.
G.f.: x*(1+2*x-2*x^2+2*x^3-2*x^4+2*x^5+x^6) / ((1-x)^3*(1+x)*(1-x+x^2)*(1+x+x^2)).
(End)
MAPLE
MATHEMATICA
Table[n^2 - 4 Floor[n^2 / 6], {n, 0, 70}] (* Vincenzo Librandi, Jan 16 2016 *)
PROG
(PARI) for (n = 0, 100, a = n^2-4*floor(n^2/6); print1(a, ", "))
(PARI) concat(0, Vec(x*(1+2*x-2*x^2+2*x^3-2*x^4+2*x^5+x^6)/((1-x)^3*(1+x)*(1-x+x^2)*(1+x+x^2)) + O(x^100))) \\ Colin Barker, Jan 16 2016
(PARI) a(n)=n^2 - n^2\6*4 \\ Charles R Greathouse IV, Mar 22 2017
(Magma) [0] cat [n^2-4*Floor(n^2/6): n in [1..70]]; // Vincenzo Librandi, Jan 16 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Kival Ngaokrajang, Jan 16 2016
STATUS
approved