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A247727 Number of length 1+3 0..n arrays with no disjoint pairs in any consecutive four terms having the same sum. 1
8, 48, 168, 440, 960, 1848, 3248, 5328, 8280, 12320, 17688, 24648, 33488, 44520, 58080, 74528, 94248, 117648, 145160, 177240, 214368, 257048, 305808, 361200, 423800, 494208, 573048, 660968, 758640, 866760, 986048, 1117248, 1261128 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = n^4 + 2*n^3 + 3*n^2 + 2*n.

Conjectures from Colin Barker, Nov 07 2018: (Start)

G.f.: 8*x*(1 + x + x^2) / (1 - x)^5.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.

(End)

EXAMPLE

Some solutions for n=6:

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

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

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

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

CROSSREFS

Row 1 of A247726.

Sequence in context: A190317 A073912 A212571 * A187174 A128796 A093199

Adjacent sequences:  A247724 A247725 A247726 * A247728 A247729 A247730

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 23 2014

STATUS

approved

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Last modified February 29 02:07 EST 2020. Contains 332353 sequences. (Running on oeis4.)