A245873 Number of length 4+2 0..n arrays with some pair in every consecutive three terms totalling exactly n.

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

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