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A200437
Number of -n..n arrays x(0..9) of 10 elements with zero sum and no two or three adjacent elements summing to zero
1
0, 23674, 1432402, 24220966, 210222830, 1206988576, 5230842688, 18491305412, 56022717236, 150412523630, 366439267062, 824236891962, 1734285496242, 3448292160196, 6530868950100, 11857838629608, 20748002017096
OFFSET
1,2
COMMENTS
Row 7 of A200430
LINKS
FORMULA
Empirical: a(n) = (124952/567)*n^9 - (282778/315)*n^8 + (4520071/1890)*n^7 - (849277/180)*n^6 + (731309/108)*n^5 - (629357/90)*n^4 + (55560059/11340)*n^3 - (870757/420)*n^2 + (50299/126)*n
EXAMPLE
Some solutions for n=3
.-3...-3...-3...-3...-3...-3...-3...-3...-3...-3...-3...-3...-3...-3...-3...-3
.-2...-2...-3...-3...-2...-2...-3...-2...-1...-3...-1...-1...-3...-2...-3...-2
.-2....0....1....0....1...-3....2....0....0....1....2....0....1...-2....0...-2
.-2...-2...-2....2....0....1....0....3...-1....1....1...-3....0....0....1....0
..1...-3...-1....2....3...-2....1....0...-1....1....3....0....1....3...-3...-1
..2....1....0....2....0....3....1...-2....0....1...-2...-1....3....1...-2...-3
..1....3....2...-3...-2....3....3....1....3...-3....3....2...-2....2....3....2
..3....3....3....2....1...-1...-2....2....1....1....1....1....0....2....3....3
..0....1....3....2....0....3....0...-1....2....3...-2....2....1....2....3....3
..2....2....0...-1....2....1....1....2....0....1...-2....3....2...-3....1....3
CROSSREFS
Sequence in context: A069334 A118061 A251855 * A223342 A179918 A168169
KEYWORD
nonn
AUTHOR
R. H. Hardin Nov 17 2011
STATUS
approved