OFFSET
3,1
COMMENTS
An occurrence of a ranpp (xy;z) in a matrix A=(a(i,j)) is a triple (a(i1,j1), a(i1,j2), a(i2,j1)) where i1<i2, j1<j2 and these elements are in the same relative order as those in the triple (x,y,z). In general, the number of m X n 0-1 matrices in question is given by (m+3)*2^(m+n-2)-2^n-2^(m+1)+4 for m>0 and n>2; for n=2 the number is (m+1)*2^m.
LINKS
S. Kitaev, On multi-avoidance of right angled numbered polyomino patterns, Integers: Electronic Journal of Combinatorial Number Theory 4 (2004), A21, 20pp.
Index entries for linear recurrences with constant coefficients, signature (3, -2).
FORMULA
a(n) = 27*2^n-28.
PROG
(PARI) vector(50, n, i=n+2; 27*2^i-28) \\ Michel Marcus, Dec 01 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Sergey Kitaev, Nov 12 2004
STATUS
approved