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A226334 Number of nondecreasing -2..2 vectors of length n whose dot product with some other -2..2 vector equals n. 2
2, 14, 23, 67, 100, 202, 281, 479, 636, 971, 1243, 1770, 2205, 2980, 3630, 4725, 5654, 7140, 8415, 10381, 12082, 14614, 16823, 20027, 22840, 26817, 30331, 35204, 39531, 45416, 50668, 57705, 64010, 72330, 79815, 89575, 98384, 109730, 120005, 133111 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 2 of A226340.
LINKS
FORMULA
Conjectures from Colin Barker, Mar 16 2018: (Start)
G.f.: x*(2 + 12*x + 5*x^2 + 20*x^3 + 13*x^4 + 2*x^5 + 12*x^6 - 2*x^7 + x^9 - 2*x^10 - x^11 + x^12) / ((1 - x)^5*(1 + x)^4*(1 + x^2)^2).
a(n) = a(n-1) + 2*a(n-2) - 2*a(n-3) + a(n-4) - a(n-5) - 4*a(n-6) + 4*a(n-7) + a(n-8) - a(n-9) + 2*a(n-10) - 2*a(n-11) - a(n-12) + a(n-13) for n>13.
(End)
EXAMPLE
Some solutions for n=3:
.-1...-1...-1....0...-1...-2...-1...-2....1....1...-2...-1...-1...-1....1...-2
..1...-1....2....1....1...-1...-1...-1....1....2...-2....0...-1....0....1....1
..2....1....2....1....1....0....0....1....2....2....1....1....2....2....1....1
CROSSREFS
Cf. A226340.
Sequence in context: A220274 A036433 A172048 * A109255 A285990 A174594
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jun 04 2013
STATUS
approved

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Last modified June 15 19:43 EDT 2024. Contains 373410 sequences. (Running on oeis4.)