A288527 Number of (undirected) paths in the grid graph P_3 X P_n.

3, 49, 322, 1618, 7119, 28917, 111360, 412998, 1490095, 5266919, 18329164, 63032354, 214788229, 726753651, 2445603148, 8194841668, 27369348241, 91175639607, 303133174298, 1006289129240, 3336552385073, 11052905264953, 36588907685926, 121056347131508

Offset

1,1

Links

Andrew Howroyd, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = 10*a(n-1)-37*a(n-2)+59*a(n-3)-27*a(n-4)-25*a(n-5)+21*a(n-6)+5*a(n-7)-4*a(n-8)-a(n-9) for n>9.

Empirical g.f.: x*(3 + 19*x - 57*x^2 + 34*x^3 + 43*x^4 - 7*x^5 - 13*x^6 - 2*x^7) / ((1 - x)^3*(1 - 2*x - x^2)^2*(1 - 3*x - x^2)). - Colin Barker, Jun 11 2017

Crossrefs

Row 3 of A288518.

Cf. A288516.

Sequence in context: A359886 A212651 A225317 * A269630 A067788 A167601

Adjacent sequences: A288524 A288525 A288526 * A288528 A288529 A288530

Keyword

nonn

Author

Andrew Howroyd, Jun 10 2017

Status

approved