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A234723
Number of (n+1) X (3+1) 0..7 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 7 (constant-stress 1 X 1 tilings).
1
4192, 12464, 33560, 116168, 360760, 1349336, 4577624, 17961560, 64580152, 261840344, 980480600, 4070568728, 15709810360, 66384051416, 262296459224, 1123428836120, 4523517191992, 19577976359384, 80058579242840
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 4*a(n-1) +137*a(n-2) -560*a(n-3) -8456*a(n-4) +35504*a(n-5) +310702*a(n-6) -1349320*a(n-7) -7561533*a(n-8) +34294092*a(n-9) +128206281*a(n-10) -615707400*a(n-11) -1548288698*a(n-12) +8040276992*a(n-13) +13333179376*a(n-14) -77453548480*a(n-15) -79946374816*a(n-16) +552146144704*a(n-17) +309222145232*a(n-18) -2893327015040*a(n-19) -567224779296*a(n-20) +10948880162304*a(n-21) -974085452928*a(n-22) -28950298675200*a(n-23) +9103597862400*a(n-24) +50436504576000*a(n-25) -24908850432000*a(n-26) -51674112000000*a(n-27) +32903055360000*a(n-28) +23410114560000*a(n-29) -17557585920000*a(n-30).
EXAMPLE
Some solutions for n=4:
5 3 7 4 1 4 2 4 1 5 1 3 4 5 4 7 0 5 0 3
0 5 2 6 4 0 5 0 5 2 5 0 7 1 7 3 4 2 4 0
3 1 5 2 4 7 5 7 1 5 1 3 3 4 3 6 0 5 0 3
1 6 3 7 6 2 7 2 7 4 7 2 6 0 6 2 4 2 4 0
3 1 5 2 2 5 3 5 0 4 0 2 3 4 3 6 2 7 2 5
CROSSREFS
Column 3 of A234728.
Sequence in context: A236805 A202530 A242770 * A152511 A252316 A103614
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 30 2013
STATUS
approved