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%I #6 Jun 15 2017 21:46:31
%S 1,4,26,307,2571,42702,3243689,132728354,1491326272,101843558868,
%T 74672717363118,12952235029243936,334070494079203752,
%U 109915013016304822208,695394278635888843298780,579704015638436450676621584,44655320458467210977882177104,75051772861714827753881814035744
%N Number of ways to reciprocally link elements of an n X n X n triangular array with themselves or a neighbor, with no more than 4 elements linked to themselves.
%C Column 4 of A271617.
%e Some solutions for n=4
%e .....5........0........0........0........0........0........0........5
%e ....2.0......4.3......0.0......6.0......0.0......4.3......6.6......2.6
%e ...5.4.3....5.0.6....5.4.3....5.1.6....6.4.3....4.3.5....5.1.1....5.0.1
%e ..2.4.3.0..2.4.3.1..2.0.4.3..2.4.3.1..0.1.4.3..4.3.2.0..2.4.3.0..2.4.3.0
%e Element moves: 0=itself 1=nw 2=ne 3=w 4=e 5=sw 6=se, reciprocals total 7
%Y Cf. A271617.
%K nonn
%O 1,2
%A _R. H. Hardin_, Apr 10 2016
%E a(15)-a(18) from _Alois P. Heinz_, Jun 15 2017
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