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A152135 Maximal length of rook tour on an n X n+4 board. 5
12, 36, 74, 134, 216, 328, 470, 650, 868, 1132, 1442, 1806, 2224, 2704, 3246, 3858, 4540, 5300, 6138, 7062, 8072, 9176, 10374, 11674, 13076, 14588, 16210, 17950, 19808, 21792, 23902, 26146, 28524, 31044, 33706, 36518, 39480, 42600, 45878 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

M. Gardner, Knotted Doughnuts and Other Mathematical Entertainments. Freeman, NY, 1986, p. 76.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (3,-2,-2,3,-1).

FORMULA

G.f.: -2*x*(-6+5*x^2-4*x^3+x^4)/(1+x)/(x-1)^4.

a(n) = +3*a(n-1) -2*a(n-2) -2*a(n-3) +3*a(n-4) -a(n-5). a(n) = 19*n/3+3/2+2*n^3/3+4*n^2+(-1)^n/2. [From R. J. Mathar, May 13 2010]

MATHEMATICA

LinearRecurrence[{3, -2, -2, 3, -1}, {12, 36, 74, 134, 216}, 40] (* Vincenzo Librandi, Dec 11 2012 *)

PROG

(MAGMA) I:=[12, 36, 74, 134, 216]; [n le 5 select I[n] else 3*Self(n-1)-2*Self(n-2)-2*Self(n-3)+3*Self(n-4)-Self(n-5): n in [1..40]]; // Vincenzo Librandi, Dec 11 2012

CROSSREFS

Cf. A006071, A152132-A152134.

Sequence in context: A043920 A049598 A342914 * A080562 A212963 A033196

Adjacent sequences:  A152132 A152133 A152134 * A152136 A152137 A152138

KEYWORD

nonn,easy

AUTHOR

R. J. Mathar, Mar 22 2009

STATUS

approved

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Last modified April 12 21:13 EDT 2021. Contains 342932 sequences. (Running on oeis4.)