The On-Line Encyclopedia of Integer Sequences (OEIS)

A058333 revision #6

A058333

Number of 3 X 3 matrices with elements from [0,...,(n-1)] satisfying the condition that the middle element of each row or column is the difference of the two end elements (in absolute value).

1, 16, 73, 208, 465, 896, 1561, 2528, 3873, 5680, 8041, 11056, 14833, 19488, 25145, 31936, 40001, 49488, 60553, 73360, 88081, 104896, 123993, 145568, 169825, 196976, 227241, 260848, 298033, 339040

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OFFSET

1,2

COMMENTS

If the "middle element" condition in the definition is also placed on the two diagonal lines of three in addition to each row and column, the sequence generated is the sequence of squares {1,4,9,16,...}.

LINKS

Table of n, a(n) for n=1..30.

FORMULA

The terms a(1) through a(30) are given by a(n)=(n^4+8n^3-10n^2+4n)/3.

Empirical g.f.: x*(x+1)*(7*x^2-10*x-1) / (x-1)^5. - Colin Barker, Mar 29 2013

CROSSREFS

Sequence in context: A299803 A299679 A300311 * A232337 A124894 A126403

Adjacent sequences: A058330 A058331 A058332 * A058334 A058335 A058336

KEYWORD

nonn

AUTHOR

John W. Layman, Dec 13 2000

STATUS

approved