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[I suspect Barker's formulas only conjectures. - N. J. A. Sloane, Jun 12 2024]
If the above formulas are true, then a(n) = (31 - 3*(-1)^n + 126*n^2 + 4*A056594(n))/16 for n > 0. - Stefano Spezia, Jun 08 2024
proposed
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B. Grünbaum, Uniform tilings of 3-space, Geombinatorics, 4 (1994), 49-56. See tiling #4.
B. Grünbaum, <a href="https://faculty.washington.edu/moishe/branko/BG199.Uniform%20Tilings%20of
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Cf. A056594.
Conjectures from _From _Colin Barker_, Feb 11 2018: (Start)
Conjecture: a(n) = (31 - 3*(-1)^n + 126*n^2 + 4*A056594(n))/16 for n > 0. - Stefano Spezia, Jun 08 2024
a(n) = 2*a(n-1) - a(n-2) + a(n-4) - 2*a(n-5) + a(n-6) for n>6. (End)
(End)
Conjecture: a(n) = (31 - 3*(-1)^n + 126*n^2 + 4*A056594(n))/16 for n > 0. - Stefano Spezia, Jun 08 2024
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(PARI) a(n)=([0, 1, 0, 0, 0, 0; 0, 0, 1, 0, 0, 0; 0, 0, 0, 1, 0, 0; 0, 0, 0, 0, 1, 0; 0, 0, 0, 0, 0, 1; 1, -2, 1, 0, -1, 2]^n*[1; 10; 33; 73; 128; 199])[1, 1] \\ Charles R Greathouse IV, Oct 18 2022
nonn,easy
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