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A228224 Number of second differences of arrays of length 9 of numbers in 0..n. 1
511, 19171, 242461, 1688101, 8006491, 29066311, 86929081, 224817481, 519682231, 1098972331, 2162213461, 4007999341, 7067000851, 11941597711, 19452737521, 30694626961, 47097859951, 70501587571, 103235334541, 148211067061 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..24

FORMULA

Empirical: a(n) = 120*n^7 - 42*n^6 - 1158*n^5 + 6945*n^4 - 13980*n^3 + 13512*n^2 - 4887*n + 1.

Conjectures from Colin Barker, Sep 10 2018: (Start)

G.f.: x*(511 + 15083*x + 103401*x^2 + 256585*x^3 + 252785*x^4 + 16749*x^5 - 40313*x^6 - x^7) / (1 - x)^8.

a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>8.

(End)

EXAMPLE

Some solutions for n=4:

.-6...-4...-8...-6...-4...-6...-6...-6...-4...-6...-6...-6...-4...-6...-4...-4

..2....2....7....6....0....5....1....6...-4....6....4....7...-2....5....2...-4

..5....2...-6...-4....0....2....0...-3....6...-4...-3...-5....4....0...-4....8

.-4...-2....3....1....3...-4....3....0...-1....1....6....3...-2...-3....5...-7

.-3....0....0...-3...-5....1...-3...-3...-1...-1...-4...-3...-1....2...-3....3

..3....2....0....3....3....0....1....3....1....4...-3....3....2...-3....0....0

.-1...-2....2....0....1...-2....0....1...-4...-4....4...-2...-4....0....4....0

CROSSREFS

Row 7 of A228218.

Sequence in context: A075944 A181128 A228265 * A022525 A069094 A024007

Adjacent sequences:  A228221 A228222 A228223 * A228225 A228226 A228227

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 16 2013

STATUS

approved

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Last modified October 18 02:23 EDT 2019. Contains 328135 sequences. (Running on oeis4.)