A247727 Number of length 1+3 0..n arrays with no disjoint pairs in any consecutive four terms having the same sum.

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

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