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.

A259221 Number of (n+1) X (7+1) 0..1 arrays with each 2 X 2 subblock having clockwise pattern 0000 0011 or 0101.

Original entry on oeis.org

311, 421, 588, 869, 1325, 2078, 3319, 5377, 8804, 14545, 24225, 40670, 68843, 117557, 202636, 352813, 620837, 1104574, 1987407, 3616121, 6651956, 12365081, 23211193, 43964734, 83952995, 161472013, 312533724, 608223317, 1189192349, 2334286430
Offset: 1

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Author

R. H. Hardin, Jun 21 2015

Keywords

Examples

			Some solutions for n=4:
  1 0 1 0 1 0 1 0     0 0 1 0 0 0 0 1     0 1 0 1 0 1 1 1
  1 0 1 0 1 0 1 0     0 0 1 0 0 0 0 1     1 0 1 0 1 0 0 0
  0 1 0 1 0 1 0 1     1 1 0 1 1 1 1 0     0 1 0 1 0 1 1 1
  1 0 1 0 1 0 1 0     0 0 1 0 0 0 0 1     1 0 1 0 1 0 0 0
  0 1 0 1 0 1 0 1     1 1 0 1 1 1 1 0     0 1 0 1 0 1 1 1
		

Crossrefs

Column 7 of A259222.

Formula

a(n) = 4*a(n-1) - 4*a(n-2) - a(n-3) + 2*a(n-4).
G.f.: x*(311 - 823*x + 148*x^2 + 512*x^3) / ((1 - x)*(1 - 2*x)*(1 - x - x^2)). - Colin Barker, Dec 24 2018
From the above formulae, a(n) = 2^(n+1) + 53*Fibonacci(n+3) + 148. - Ehren Metcalfe, Dec 27 2018