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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

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

Adjacent sequences:  A234720 A234721 A234722 * A234724 A234725 A234726

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 30 2013

STATUS

approved

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Last modified August 16 05:16 EDT 2022. Contains 356162 sequences. (Running on oeis4.)