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%I #8 Sep 27 2015 17:42:31
%S 17,131,9985,316686,9787192,118474944,10608304158,137343065266,
%T 10377510294334,104208752940208,17201597741284536,188513786701536807,
%U 26630716056607954131,232536991177649068440,62398022471626643456428
%N Number of (n+2)X(n+2) nonnegative integer arrays with all values the knight distance from the upper left minus as much as 1, with successive minimum path knight move differences either 0 or +1, and any unreachable value zero.
%C Diagonal of A253424.
%H R. H. Hardin, <a href="/A253416/b253416.txt">Table of n, a(n) for n = 1..21</a>
%e Some solutions for n=2
%e ..0..3..1..4....0..3..1..4....0..3..2..4....0..2..2..4....0..3..2..4
%e ..2..3..1..2....2..3..1..2....2..3..1..2....3..3..1..1....2..3..1..2
%e ..2..1..3..2....2..1..3..2....2..1..3..2....1..1..3..2....2..1..3..2
%e ..4..2..2..2....4..2..2..1....4..1..3..1....4..2..2..1....4..2..2..2
%e Knight distance matrix for n=2
%e ..0..3..2..5
%e ..3..4..1..2
%e ..2..1..4..3
%e ..5..2..3..2
%K nonn
%O 1,1
%A _R. H. Hardin_, Dec 31 2014