cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A203084 Number of (n+2) X 3 binary arrays avoiding patterns 000 and 101 in rows and columns.

Original entry on oeis.org

98, 253, 621, 1575, 4000, 10057, 25384, 64140, 161819, 408415, 1031041, 2602296, 6568305, 16579362, 41847510, 105626421, 266611217, 672949667, 1698582936, 4287374163, 10821707646, 27314936026, 68945297129, 174023973205
Offset: 1

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Author

R. H. Hardin, Dec 29 2011

Keywords

Comments

Column 1 of A203091.

Examples

			Some solutions for n=3:
  1 0 0    1 1 0    1 1 0    0 1 0    0 0 1    1 1 1    1 0 0
  1 1 0    1 1 0    1 1 1    1 0 0    1 1 1    1 1 0    1 1 0
  1 1 1    1 1 1    1 1 1    0 0 1    1 0 0    1 1 0    0 1 1
  1 1 1    0 1 1    1 1 1    0 1 1    1 0 0    0 1 1    0 1 1
  0 1 0    0 0 1    0 1 0    1 1 0    0 1 1    0 0 1    1 0 0
		

Crossrefs

Cf. A203091.

Formula

Empirical: a(n) = a(n-1) + a(n-2) + 6*a(n-3) + 2*a(n-4) + 3*a(n-5) - a(n-6) - a(n-8) - a(n-9) - a(n-10).
Empirical g.f.: x*(98 + 155*x + 270*x^2 + 113*x^3 + 90*x^4 - 44*x^5 - 26*x^6 - 61*x^7 - 53*x^8 - 36*x^9) / (1 - x - x^2 - 6*x^3 - 2*x^4 - 3*x^5 + x^6 + x^8 + x^9 + x^10). - Colin Barker, Mar 03 2018