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A258547
Number of (n+1)X(1+1) 0..1 arrays with every 2X2 subblock ne-sw antidiagonal difference nondecreasing horizontally and nw+se diagonal sum nondecreasing vertically
2
16, 44, 104, 228, 480, 988, 2008, 4052, 8144, 16332, 32712, 65476, 131008, 262076, 524216, 1048500, 2097072, 4194220, 8388520, 16777124, 33554336, 67108764, 134217624, 268435348, 536870800, 1073741708, 2147483528, 4294967172
OFFSET
1,1
COMMENTS
Column 1 and row 1 of A258554
LINKS
FORMULA
Empirical: a(n) = 4*a(n-1) -5*a(n-2) +2*a(n-3)
a(n) = 16*2^n - 4*n - 12. - Michael Somos, Oct 14 2020
EXAMPLE
Some solutions for n=4
..0..0....0..1....0..1....0..0....0..0....0..1....1..0....0..0....0..1....0..1
..0..1....0..1....1..0....0..0....1..1....0..0....1..0....1..0....0..1....0..0
..1..1....0..1....1..0....1..1....0..0....1..0....1..1....1..0....1..1....0..0
..1..0....1..1....0..0....1..0....0..1....1..1....1..1....0..0....1..0....1..0
..0..0....0..1....0..1....0..1....1..1....1..1....0..1....1..1....1..0....1..1
PROG
(PARI) {a(n) = if(n<-2, 0, 16*2^n - 4*n - 12)}; /* Michael Somos, Oct 14 2020 */
CROSSREFS
Sequence in context: A210375 A173560 A293858 * A211573 A211582 A204032
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jun 03 2015
STATUS
approved