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A269607 Number of length-4 0..n arrays with no repeated value differing from the previous repeated value by one or less. 1
8, 62, 222, 572, 1220, 2298, 3962, 6392, 9792, 14390, 20438, 28212, 38012, 50162, 65010, 82928, 104312, 129582, 159182, 193580, 233268, 278762, 330602, 389352, 455600, 529958, 613062, 705572, 808172, 921570, 1046498, 1183712, 1333992 (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 + 4*n^3 + 4*n^2 - n.

Conjectures from Colin Barker, Jan 25 2019: (Start)

G.f.: 2*x*(4 + 11*x - 4*x^2 + x^3) / (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=7:

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

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

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

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

CROSSREFS

Row 4 of A269606.

Sequence in context: A082179 A114028 A044527 * A296584 A198690 A056054

Adjacent sequences:  A269604 A269605 A269606 * A269608 A269609 A269610

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 01 2016

STATUS

approved

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Last modified June 19 03:38 EDT 2021. Contains 345125 sequences. (Running on oeis4.)