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A194773
Number of lower triangles of an (n+4) X (n+4) 0..3 array with new values introduced in row major order 0..3 and no element unequal to more than one horizontal or vertical neighbor.
1
43, 105, 265, 655, 1641, 4069, 10121, 25025, 61809, 152019, 372979, 912017, 2224175, 5408825, 13120905, 31752431, 76673045, 184762437, 444388957, 1066954113, 2557518625, 6121119363, 14629468735, 34918297649, 83242029523, 198212839881
OFFSET
1,1
COMMENTS
Column 3 of A194778.
LINKS
FORMULA
Empirical: a(n) = 5*a(n-1) -2*a(n-2) -22*a(n-3) +21*a(n-4) +35*a(n-5) -34*a(n-6) -26*a(n-7) +15*a(n-8) +9*a(n-9).
Empirical g.f.: x*(43 - 110*x - 174*x^2 + 486*x^3 + 303*x^4 - 706*x^5 - 310*x^6 + 318*x^7 + 153*x^8) / ((1 - x)*(1 - x - x^2)^2*(1 - x - 3*x^2)^2). - Colin Barker, May 05 2018
EXAMPLE
All solutions for 5 X 5 including a 3:
0 0
1 1 1 1
1 1 2 1 1 1
1 1 2 2 2 2 2 2
1 1 2 2 3 2 2 2 2 3
CROSSREFS
Cf. A194778.
Sequence in context: A325077 A023293 A115606 * A154506 A044230 A044611
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 02 2011
STATUS
approved