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A249234 Number of length 1+5 0..n arrays with no six consecutive terms having two times the sum of any two elements equal to the sum of the remaining four. 1
42, 486, 2772, 10620, 32070, 81402, 183696, 376752, 718530, 1289430, 2201892, 3603396, 5688582, 8702250, 12954360, 18823392, 26773506, 37358622, 51242100, 69200820, 92147742, 121136346, 157385352, 202283880, 257418690, 324579342 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..92

FORMULA

Empirical: a(n) = 4*a(n-1) - 4*a(n-2) - 3*a(n-3) + 6*a(n-4) - 6*a(n-7) + 3*a(n-8) + 4*a(n-9) - 4*a(n-10) + a(n-11).

Empirical for n mod 6 = 0: a(n) = n^6 + (1/4)*n^5 + (115/4)*n^4 - (80/3)*n^3 + 35*n^2 + 7*n

Empirical for n mod 6 = 1: a(n) = n^6 + (1/4)*n^5 + (115/4)*n^4 - (80/3)*n^3 + 35*n^2 + (163/4)*n - (445/12)

Empirical for n mod 6 = 2: a(n) = n^6 + (1/4)*n^5 + (115/4)*n^4 - (80/3)*n^3 + 35*n^2 + 7*n + (40/3)

Empirical for n mod 6 = 3: a(n) = n^6 + (1/4)*n^5 + (115/4)*n^4 - (80/3)*n^3 + 35*n^2 + (163/4)*n - (255/4)

Empirical for n mod 6 = 4: a(n) = n^6 + (1/4)*n^5 + (115/4)*n^4 - (80/3)*n^3 + 35*n^2 + 7*n + (80/3)

Empirical for n mod 6 = 5: a(n) = n^6 + (1/4)*n^5 + (115/4)*n^4 - (80/3)*n^3 + 35*n^2 + (163/4)*n - (605/12).

Empirical g.f.: 6*x*(7 + 53*x + 166*x^2 + 267*x^3 + 314*x^4 + 167*x^5 + 266*x^6 + 53*x^7 + 147*x^8) / ((1 - x)^7*(1 + x)^2*(1 + x + x^2)). - Colin Barker, Nov 09 2018

EXAMPLE

Some solutions for n=7:

  6  4  6  2  2  0  6  2  4  0  6  4  6  2  1  4

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

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

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

  1  7  2  2  0  4  6  6  3  6  4  6  2  6  7  3

  5  2  5  6  2  7  2  3  3  3  6  7  7  2  0  2

CROSSREFS

Row 1 of A249233.

Sequence in context: A216113 A204566 A249233 * A250324 A086944 A263289

Adjacent sequences:  A249231 A249232 A249233 * A249235 A249236 A249237

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 23 2014

STATUS

approved

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Last modified January 23 04:16 EST 2020. Contains 331168 sequences. (Running on oeis4.)