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A268952 Number of length-n 0..4 arrays with no repeated value equal to the previous repeated value, with new values introduced in sequential order. 1
1, 2, 4, 12, 40, 153, 634, 2785, 12634, 58409, 272738, 1280233, 6024682, 28383609, 133772018, 630473513, 2970963898, 13996752665, 65924951490, 310433985929, 1461486107146, 6879181490937, 32374728610962, 152339562845289 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
Empirical: a(n) = 11*a(n-1) -31*a(n-2) -41*a(n-3) +268*a(n-4) -90*a(n-5) -692*a(n-6) +512*a(n-7) +576*a(n-8) -512*a(n-9) for n>11.
Empirical g.f.: x*(1 - 9*x + 13*x^2 + 71*x^3 - 154*x^4 - 197*x^5 + 483*x^6 + 210*x^7 - 546*x^8 - 24*x^9 + 192*x^10) / ((1 - x)*(1 - 2*x)*(1 - 4*x)*(1 - 2*x^2)*(1 - x - 4*x^2)*(1 - 3*x - 8*x^2)). - Colin Barker, Jan 17 2019
EXAMPLE
Some solutions for n=8:
..0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0. .0
..1. .0. .1. .1. .1. .1. .1. .1. .1. .1. .1. .1. .0. .1. .1. .1
..2. .1. .1. .2. .2. .2. .1. .2. .0. .2. .0. .2. .1. .0. .0. .2
..1. .2. .2. .3. .1. .3. .2. .2. .2. .1. .2. .1. .0. .2. .2. .0
..3. .0. .1. .4. .2. .2. .1. .3. .1. .3. .0. .3. .1. .2. .3. .1
..4. .1. .3. .0. .0. .4. .2. .3. .1. .1. .3. .0. .2. .3. .4. .1
..2. .2. .4. .1. .1. .3. .1. .4. .3. .0. .3. .3. .2. .4. .2. .2
..0. .2. .0. .3. .0. .1. .0. .4. .2. .2. .1. .2. .1. .0. .1. .0
CROSSREFS
Column 4 of A268956.
Sequence in context: A211965 A119430 A074034 * A215072 A326513 A268953
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 16 2016
STATUS
approved

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Last modified February 28 22:27 EST 2024. Contains 370400 sequences. (Running on oeis4.)