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A247117
Number of tilings of a 10 X n rectangle using 2n pentominoes of shape I.
4
1, 1, 1, 1, 1, 8, 17, 28, 41, 56, 144, 317, 609, 1060, 1716, 3324, 6713, 13188, 24624, 43620, 80464, 153645, 296025, 562097, 1037921, 1920661, 3600832, 6820873, 12920804, 24211457, 45173688, 84493668, 158848825, 299451277, 562923960, 1055117520, 1976475968
OFFSET
0,6
LINKS
Wikipedia, Pentomino
FORMULA
G.f.: see Maple program.
MAPLE
gf:= -(x^10+x^8-x^6-2*x^5-x^4-x^3+1) *(x-1)^4 *(x^4+x^3+x^2+x+1)^4 / (x^35 +x^33 -2*x^31 -7*x^30 -2*x^29 -6*x^28 +x^27 +9*x^26 +22*x^25 +8*x^24 +15*x^23 -4*x^22 -15*x^21 -39*x^20 -12*x^19 -20*x^18 +6*x^17 +10*x^16 +45*x^15 +8*x^14 +19*x^13 -4*x^12 -4*x^11 -33*x^10 -6*x^9 -10*x^8 +x^7 -3*x^6 +12*x^5 +x^3 +x-1):
a:= n-> coeff(series(gf, x, n+1), x, n):
seq(a(n), n=0..50);
CROSSREFS
Cf. A174249, A233427, A003520 (5 X n), A247218 (15 X n).
Column k=5 of A250662.
Sequence in context: A264355 A028884 A322473 * A099358 A077222 A077221
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Nov 19 2014
STATUS
approved