A224349 - OEIS

%I #6 Sep 04 2022 08:11:06

%S 15,225,2321,19608,160362,1351748,11704964,102319662,895494806,

%T 7833508842,68530349850,599768316699,5250822841015,45977188883801,

%U 402610713736831,3525653178203557,30874547729660838,270374890703092436

%N Number of n X 4 0..2 arrays with diagonals and antidiagonals unimodal and rows nondecreasing.

%C Column 4 of A224353.

%H R. H. Hardin, <a href="/A224349/b224349.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 15*a(n-1) -58*a(n-2) -13*a(n-3) +543*a(n-4) -1609*a(n-5) +1864*a(n-6) -17378*a(n-7) +62814*a(n-8) +73709*a(n-9) -307108*a(n-10) +721338*a(n-11) -862742*a(n-12) +4668915*a(n-13) -12478479*a(n-14) -3206649*a(n-15) +1858428*a(n-16) +5104796*a(n-17) +28929803*a(n-18) +21290844*a(n-19) +12857067*a(n-20) -28005842*a(n-21) -37205324*a(n-22) -26318800*a(n-23) -9161072*a(n-24) -1481856*a(n-25) -6336*a(n-26).

%e Some solutions for n=3

%e ..0..0..1..1....1..1..1..1....0..0..2..2....0..1..1..2....0..0..1..1

%e ..0..0..0..0....0..1..1..1....0..0..1..2....0..1..1..1....1..2..2..2

%e ..0..0..1..2....1..1..1..1....0..0..0..0....1..1..1..1....0..1..1..2

%Y Cf. A224353.

%K nonn

%O 1,1

%A _R. H. Hardin_, Apr 04 2013