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Revision History for A296997 (Bold, blue-underlined text is an addition; faded, red-underlined text is a deletion.)

Showing entries 1-10 | older changes
Number of ways to place 3 points on an n X n point grid so that no point is equally distant from two other points on the same row or the same column.
(history; published version)
#23 by Bruno Berselli at Tue Jan 16 03:15:20 EST 2018
STATUS

reviewed

approved

#22 by Joerg Arndt at Tue Jan 16 03:14:39 EST 2018
STATUS

proposed

reviewed

#21 by Heinrich Ludwig at Mon Jan 15 17:00:46 EST 2018
STATUS

editing

proposed

#20 by Robert G. Wilson v at Mon Jan 15 14:12:39 EST 2018
MATHEMATICA

CoefficientList[ Series[-2x (2 + 29x + 93x^2 + 82x^3 + 32x^4 + x^5 + x^6)/((x - 1)^7 (x + 1)^2), {x, 0, 31}], x] (* _Robert G. Wilson v_, Jan 15 2018 or *)

LinearRecurrence[{5, -8, 0, 14, -14, 0, 8, -5, 1}, {0, 4, 78, 544, 2260, 7068, 18298, 41472, 85032}, 32] (* Robert G. Wilson v, Jan 15 2018 *)

#19 by Robert G. Wilson v at Mon Jan 15 14:10:38 EST 2018
MATHEMATICA

CoefficientList[ Series[-2x (2 + 29x + 93x^2 + 82x^3 + 32x^4 + x^5 + x^6)/((x - 1)^7 (x + 1)^2), {x, 0, 31}], x] (* Robert G. Wilson v, Jan 15 2018 *)

STATUS

proposed

editing

#18 by Heinrich Ludwig at Sat Jan 13 06:41:43 EST 2018
STATUS

editing

proposed

#17 by Heinrich Ludwig at Sat Jan 13 06:37:57 EST 2018
FORMULA

a(n) = (n^6 - 3*n^4 - 3*n^3 + 8*n^2)/6 for n even,

a(n) = (n^6 - 3*n^4 - 3*n^3 + 8*n^2 - 3*n)/6 for n odd.

STATUS

proposed

editing

Discussion
Sat Jan 13
06:41
Heinrich Ludwig: Formula splitted for n even and odd. Following suggestions of editors proposed for similar formulae.
#16 by Heinrich Ludwig at Fri Jan 12 12:51:46 EST 2018
STATUS

editing

proposed

#15 by Heinrich Ludwig at Fri Jan 12 12:51:23 EST 2018
COMMENTS

Rotations and reflections of a placement are counted. If they are to be ignored, see A296996.

CROSSREFS
STATUS

proposed

editing

Discussion
Fri Jan 12
12:51
Heinrich Ludwig: Cf. added
#14 by Jon E. Schoenfield at Mon Jan 01 23:41:45 EST 2018
STATUS

editing

proposed