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A220618 Number of ways to reciprocally link elements of an nX5 array either to themselves or to exactly one horizontal, diagonal and antidiagonal neighbor.

%I A220618 #6 Jul 23 2025 01:18:07
%S A220618 8,317,9176,282777,8608738,262680517,8011414792,244357686173,
%T A220618 7453056468816,227323314349577,6933510501158596,211476640729594693,
%U A220618 6450176661330373022,196734631145079828705,6000535646826871036976
%N A220618 Number of ways to reciprocally link elements of an nX5 array either to themselves or to exactly one horizontal, diagonal and antidiagonal neighbor.
%C A220618 Column 5 of A220621
%H A220618 R. H. Hardin, <a href="/A220618/b220618.txt">Table of n, a(n) for n = 1..210</a>
%F A220618 Empirical: a(n) = 38*a(n-1) -189*a(n-2) -1434*a(n-3) +6910*a(n-4) -3882*a(n-5) -9380*a(n-6) +9742*a(n-7) -477*a(n-8) -1476*a(n-9) +125*a(n-10)
%e A220618 Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)
%e A220618 ..0..0..9..9..0....0..0..0..6..4....6..4..7..0..0....0..0..6..4..0
%e A220618 ..0..7..0..1..1....0..6..4..9..0....9..3..0..9..0....9..6..4..6..4
%e A220618 ..3..0..6..4..0....0..0..0..0..1....0..1..0..0..1....0..1..0..0..0
%K A220618 nonn
%O A220618 1,1
%A A220618 _R. H. Hardin_ Dec 17 2012