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A263795 Number of (n+1)X(4+1) 0..1 arrays with each row and column divisible by 3, read as a binary number with top and left being the most significant bits, and rows and columns lexicographically nonincreasing.

%I A263795 #6 Jul 23 2025 15:38:44
%S A263795 3,3,7,7,17,18,56,66,218,272,798,1008,2567,3227,7290,9072,18622,22912,
%T A263795 43560,52998,94678,113983,193427,230607,374843,442911,694073,813413,
%U A263795 1235202,1436754,2122943,2452403,3537837,4061097,5735701,6545785,9072159
%N A263795 Number of (n+1)X(4+1) 0..1 arrays with each row and column divisible by 3, read as a binary number with top and left being the most significant bits, and rows and columns lexicographically nonincreasing.
%C A263795 Column 4 of A263799
%H A263795 R. H. Hardin, <a href="/A263795/b263795.txt">Table of n, a(n) for n = 1..210</a>
%F A263795 Empirical: a(n) = a(n-1) +9*a(n-2) -9*a(n-3) -36*a(n-4) +36*a(n-5) +84*a(n-6) -84*a(n-7) -126*a(n-8) +126*a(n-9) +126*a(n-10) -126*a(n-11) -84*a(n-12) +84*a(n-13) +36*a(n-14) -36*a(n-15) -9*a(n-16) +9*a(n-17) +a(n-18) -a(n-19)
%e A263795 Some solutions for n=5
%e A263795 ..1..1..0..0..0....0..0..0..0..0....1..1..1..1..0....1..1..0..0..0
%e A263795 ..1..1..0..0..0....0..0..0..0..0....1..1..1..1..0....1..1..0..0..0
%e A263795 ..1..1..0..0..0....0..0..0..0..0....1..1..0..0..0....1..1..0..0..0
%e A263795 ..1..1..0..0..0....0..0..0..0..0....1..1..0..0..0....1..1..0..0..0
%e A263795 ..1..1..0..0..0....0..0..0..0..0....0..0..1..1..0....0..0..0..0..0
%e A263795 ..1..1..0..0..0....0..0..0..0..0....0..0..1..1..0....0..0..0..0..0
%Y A263795 Cf. A263799
%K A263795 nonn
%O A263795 1,1
%A A263795 _R. H. Hardin_, Oct 26 2015