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A228214 Number of second differences of arrays of length n + 2 of numbers in 0..4. 1
17, 177, 1429, 9705, 58141, 320481, 1688101, 8717049, 44633821, 227363409, 1153594261, 5835080169, 29443836301, 148292923329, 745759583941, 3745977788889, 18798608421181, 94267920012849, 472439111692021 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..137

FORMULA

Empirical: a(n) = 9*a(n-1) - 20*a(n-2) for n>9.

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

G.f.: x*(17 + 24*x + 176*x^2 + 384*x^3 - 624*x^4 - 8688*x^5 - 33408*x^6 - 66240*x^7 - 57600*x^8) / ((1 - 4*x)*(1 - 5*x)).

a(n) = 5^(2+n) - 4^(2+n) for  n>7.

(End)

EXAMPLE

Some solutions for n=4:

..8....5...-1...-2....4...-2....3....0...-2...-6....2....0....4...-5....0...-5

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

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

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

CROSSREFS

Column 4 of A228218.

Sequence in context: A173647 A119343 A164744 * A246058 A121793 A042985

Adjacent sequences:  A228211 A228212 A228213 * A228215 A228216 A228217

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 16 2013

STATUS

approved

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Last modified May 26 00:32 EDT 2020. Contains 334613 sequences. (Running on oeis4.)