A228462 Number of arrays of maxima of three adjacent elements of some length 7 0..n array.

17, 91, 310, 821, 1847, 3703, 6812, 11721, 19117, 29843, 44914, 65533, 93107, 129263, 175864, 235025, 309129, 400843, 513134, 649285, 812911, 1007975, 1238804, 1510105, 1826981, 2194947, 2619946, 3108365, 3667051, 4303327, 5025008, 5840417

Offset

1,1

Links

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

Formula

Empirical: a(n) = (2/15)*n^5 + (7/6)*n^4 + (25/6)*n^3 + (19/3)*n^2 + (21/5)*n + 1.

Conjectures from Colin Barker, Sep 11 2018: (Start)

G.f.: x*(17 - 11*x + 19*x^2 - 14*x^3 + 6*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:
..2....2....0....2....3....4....4....3....3....4....4....4....4....2....4....1
..0....1....0....1....3....4....4....1....1....2....2....3....2....1....0....4
..2....1....1....0....2....3....3....2....1....0....2....1....1....2....1....4
..3....0....3....2....2....2....2....2....1....2....1....3....2....2....1....4
..3....0....3....4....1....2....1....4....0....3....2....4....4....2....2....0

Crossrefs

Row 5 of A228461.

Sequence in context: A159676 A061971 A061222 * A217641 A213574 A253259

Adjacent sequences: A228459 A228460 A228461 * A228463 A228464 A228465

Keyword

nonn

Author

R. H. Hardin, Aug 22 2013

Status

approved