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A221541 Number of 0..7 arrays of length n with each element differing from at least one neighbor by something other than 1, starting with 0. 1
0, 7, 44, 350, 2658, 20386, 156098, 1195561, 9156379, 70126074, 537074685, 4113296146, 31502516844, 241268447450, 1847803587081, 14151780448318, 108384295414048, 830083220654363, 6357361558503534, 48689149448999134 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 7 of A221542.

LINKS

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

FORMULA

Empirical: a(n) = 7*a(n-1) +4*a(n-2) +5*a(n-3) +20*a(n-4) +20*a(n-5) +23*a(n-6) -6*a(n-7) +3*a(n-8).

Empirical g.f.: x^2*(7 - 5*x + 14*x^2 - 3*x^3 + 20*x^4 - 6*x^5) / (1 - 7*x - 4*x^2 - 5*x^3 - 20*x^4 - 20*x^5 - 23*x^6 + 6*x^7 - 3*x^8). - Colin Barker, Oct 18 2017

EXAMPLE

Some solutions for n=6

..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0

..4....7....6....3....0....4....3....2....0....0....0....2....4....2....3....4

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

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

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

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

CROSSREFS

Sequence in context: A093738 A091127 A166775 * A327680 A156374 A171493

Adjacent sequences:  A221538 A221539 A221540 * A221542 A221543 A221544

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 19 2013

STATUS

approved

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Last modified June 18 20:45 EDT 2021. Contains 345121 sequences. (Running on oeis4.)