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A245873 Number of length 4+2 0..n arrays with some pair in every consecutive three terms totalling exactly n. 1
26, 239, 676, 1629, 3102, 5515, 8840, 13625, 19810, 28071, 38316, 51349, 67046, 86339, 109072, 136305, 167850, 204895, 247220, 296141, 351406, 414459, 485016, 564649, 653042, 751895, 860860, 981765, 1114230, 1260211, 1419296, 1593569 (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) = 3*a(n-1) - a(n-2) - 5*a(n-3) + 5*a(n-4) + a(n-5) - 3*a(n-6) + a(n-7).

Conjectures from Colin Barker, Nov 04 2018: (Start)

G.f.: x*(26 + 161*x - 15*x^2 - 30*x^3 - 44*x^4 - 3*x^5 + x^6) / ((1 - x)^5*(1 + x)^2).

a(n) = 1 + 7*n + 20*n^2 + 16*n^3 + n^4 for n even.

a(n) = -8 - 3*n + 20*n^2 + 16*n^3 + n^4 for n odd.

(End)

EXAMPLE

Some solutions for n=10:

   0   6   8   3   8   4   7   8   7   1   8  10   4   3   7   1

  10   5   6  10   6   2   3   9   4   0   1   2   5   3   4   0

   4   4   4   0   4   6   3   1   3  10   9   8   5   7   6  10

   6   5  10   7   4   8   7   1   7   1   3   7   3   3  10   0

   1   5   0  10   6   2   6   9   8   0   7   3   7   1   0   4

   4   8   7   0   0   0   4   7   3  10   7   4   9   7   9  10

CROSSREFS

Row 4 of A245869.

Sequence in context: A196638 A163726 A293614 * A275880 A020537 A184461

Adjacent sequences:  A245870 A245871 A245872 * A245874 A245875 A245876

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 04 2014

STATUS

approved

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Last modified June 18 03:46 EDT 2021. Contains 345098 sequences. (Running on oeis4.)