A298795 Coordination sequence for the bil tiling (or net) with respect to a trivalent node of the fourth type.

1, 3, 6, 8, 11, 16, 19, 18, 23, 30, 29, 30, 35, 42, 43, 40, 47, 52, 55, 56, 55, 64, 67, 68, 71, 72, 79, 78, 83, 90, 85, 90, 95, 102, 103, 96, 107, 112, 115, 116, 111, 124, 127, 128, 131, 128, 139, 138, 143, 150, 141, 150, 155, 162, 163, 152, 167, 172, 175, 176

Offset

0,2

Links

Rémy Sigrist, Table of n, a(n) for n = 0..1000

Reticular Chemistry Structure Resource (RCSR), The bil tiling (or net)

Rémy Sigrist, Illustration of first terms

Rémy Sigrist, PARI program for A298795

Formula

Conjectures from Colin Barker, Mar 30 2018: (Start)

G.f.: (1 + 2*x + 5*x^2 + 6*x^3 + 11*x^4 + 12*x^5 + 15*x^6 + 12*x^7 + 19*x^8 + 12*x^9 + 15*x^10 + 12*x^11 + 11*x^12 + 8*x^13 + 5*x^14 + 2*x^15 + x^16 - x^18) / ((1 - x)^2*(1 + x^2)*(1 - x + x^2 - x^3 + x^4)*(1 + x + x^2 + x^3 + x^4)^2).

a(n) = a(n-1) - 2*a(n-2) + 2*a(n-3) - 2*a(n-4) + 3*a(n-5) - 3*a(n-6) + 4*a(n-7) - 4*a(n-8) + 4*a(n-9) - 3*a(n-10) + 3*a(n-11) - 2*a(n-12) + 2*a(n-13) - 2*a(n-14) + a(n-15) - a(n-16) for n>16.

(End)

Prog

(PARI) See Links section.

Crossrefs

Cf. A298792, A298793, A298794.

Sequence in context: A276583 A135736 A036434 * A140400 A190430 A188018

Adjacent sequences: A298792 A298793 A298794 * A298796 A298797 A298798

Keyword

nonn

Author

N. J. A. Sloane, Jan 27 2018

Extensions

More terms from Rémy Sigrist, Mar 30 2018

Status

approved