A280400 - OEIS

A280400

Number of 2Xn 0..2 arrays with no element unequal to a strict majority of its horizontal and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.

0, 2, 6, 16, 34, 76, 158, 336, 698, 1460, 3030, 6296, 13042, 27004, 55822, 115296, 237866, 490308, 1009734, 2077736, 4271970, 8776972, 18019966, 36972016, 75808154, 155344596, 318145718, 651204536, 1332235218, 2724122780, 5567550190

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OFFSET

1,2

COMMENTS

Row 2 of A280398.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 3*a(n-1) +a(n-2) -7*a(n-3) +4*a(n-5).

Empirical g.f.: 2*x^2*(-1+2*x^2+3*x^3) / ( (x-1)*(1+x)^2*(2*x-1)^2 ). - R. J. Mathar, Jan 04 2017

Empirical: a(n) = 2^(n-1)*n/9 +2^(n-1)*47/27 +(-1)^n*2*n/9 -10*(-1)^n/27-2. - R. J. Mathar, Jan 04 2017

EXAMPLE