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A223871 Number of n X 3 0..3 arrays with rows, diagonals and antidiagonals unimodal.

%I A223871 #7 Jun 26 2025 13:18:37
%S A223871 50,2500,99223,3863372,152918517,6066668157,240345697904,
%T A223871 9519219712534,377068749332794,14936662560715369,591673197324653702,
%U A223871 23437360043162717039,928401612451857089159,36775894520547706164712
%N A223871 Number of n X 3 0..3 arrays with rows, diagonals and antidiagonals unimodal.
%C A223871 Column 3 of A223876.
%H A223871 R. H. Hardin, <a href="/A223871/b223871.txt">Table of n, a(n) for n = 1..210</a>
%F A223871 Empirical: a(n) = 40*a(n-1) -132*a(n-2) +4459*a(n-3) +13745*a(n-4) -279374*a(n-5) -216409*a(n-6) -10116301*a(n-7) -38256907*a(n-8) +322157439*a(n-9) +897495274*a(n-10) +3199485479*a(n-11) +15600399494*a(n-12) -40103358672*a(n-13) -213466075938*a(n-14) -190360919826*a(n-15) -232629523048*a(n-16) +234440936372*a(n-17) +1759786495760*a(n-18) +1770736417792*a(n-19) +1582997734272*a(n-20) +781069335952*a(n-21) -1858101760192*a(n-22) -2045017763520*a(n-23) -1010972140800*a(n-24) -530550835200*a(n-25) +130955034624*a(n-26) +240537600000*a(n-27) +51314688000*a(n-28).
%e A223871 Some solutions for n=3
%e A223871 ..2..2..3....1..1..2....3..3..1....3..1..0....3..1..0....1..2..0....3..3..3
%e A223871 ..0..3..1....0..2..1....2..3..2....2..3..3....3..2..2....2..3..0....2..2..0
%e A223871 ..2..3..1....3..3..0....2..3..2....3..2..0....2..1..0....1..3..2....1..3..2
%Y A223871 Cf. A223876.
%K A223871 nonn
%O A223871 1,1
%A A223871 _R. H. Hardin_, Mar 28 2013