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 A201815 Number of arrays of 7 integers in -n..n with sum zero and equal numbers of elements greater than zero and less than zero. 1
 393, 4145, 23857, 90609, 263201, 637393, 1355145, 2613857, 4675609, 7876401, 12635393, 19464145, 28975857, 41894609, 59064601, 81459393, 110191145, 146519857, 191862609, 247802801, 316099393, 398696145, 497730857, 615544609 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Row 7 of A201811. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 77*n^5 + 175*n^3 + 140*n + 1. Conjectures from Colin Barker, May 25 2018: (Start) G.f.: x*(393 + 1787*x + 4882*x^2 + 1782*x^3 + 397*x^4 - x^5) / (1 - x)^6. a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6. (End) EXAMPLE Some solutions for n=4. ..1....3....0....1....4...-4...-4....3...-2....0....2....2...-3....4....4....4 ..2....1...-3...-1....3....4....1...-3....0....1...-3...-3....2....3...-3....1 ..0...-3...-4...-2...-4....4....4...-3....1....4....0...-1...-3....0....0...-2 ..4....0....4...-3...-4...-3...-3....3...-4...-2....2....1....0....2....0...-3 .-3...-2...-3....3....4....0....4....0....3...-1...-1....0....3...-3....0...-4 .-1...-2....2....2...-3....1....0...-1....4....1...-1...-3...-2...-2...-3....0 .-3....3....4....0....0...-2...-2....1...-2...-3....1....4....3...-4....2....4 CROSSREFS Cf. A201811. Sequence in context: A083752 A047825 A227942 * A201554 A172636 A202046 Adjacent sequences: A201812 A201813 A201814 * A201816 A201817 A201818 KEYWORD nonn AUTHOR R. H. Hardin, Dec 05 2011 STATUS approved

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Last modified August 10 00:01 EDT 2024. Contains 375044 sequences. (Running on oeis4.)