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A253327 Number of (2+1)X(n+1) 0..1 arrays with every 2X2 subblock sum nondecreasing horizontally, vertically and antidiagonally ne-to-sw 1

%I

%S 44,126,373,1026,2797,6936,17197,39616,91571,200800,442031,937998,

%T 1997242,4147312,8635487,17680582,36274902,73603454,149571217,

%U 301772250,609502075,1225424712,2465561705,4946547564,9928863677,19894339804

%N Number of (2+1)X(n+1) 0..1 arrays with every 2X2 subblock sum nondecreasing horizontally, vertically and antidiagonally ne-to-sw

%C Row 2 of A253326

%H R. H. Hardin, <a href="/A253327/b253327.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) +8*a(n-2) -50*a(n-3) -9*a(n-4) +270*a(n-5) -128*a(n-6) -820*a(n-7) +709*a(n-8) +1520*a(n-9) -1824*a(n-10) -1722*a(n-11) +2797*a(n-12) +1070*a(n-13) -2696*a(n-14) -160*a(n-15) +1608*a(n-16) -240*a(n-17) -544*a(n-18) +160*a(n-19) +80*a(n-20) -32*a(n-21)

%e Some solutions for n=4

%e ..0..0..1..0..0....1..0..1..1..0....0..0..0..0..1....1..1..0..0..0

%e ..0..1..0..1..1....0..0..0..0..1....1..0..1..1..1....0..0..1..1..1

%e ..1..1..1..1..0....1..1..1..1..1....0..0..1..1..1....1..1..1..1..1

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 30 2014

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Last modified August 14 06:54 EDT 2022. Contains 356110 sequences. (Running on oeis4.)