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A250664 Number of tilings of a 14 X n rectangle using 2n heptominoes of shape I. 3
1, 1, 1, 1, 1, 1, 1, 10, 21, 34, 49, 66, 85, 106, 256, 535, 985, 1654, 2596, 3871, 5545, 9391, 16956, 30589, 53481, 89851, 145152, 226297, 364656, 610062, 1045297, 1799392, 3065145, 5121255, 8359876, 13624960, 22431292, 37434945, 63098713, 106641142, 179356873 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,8

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Wikipedia, Heptomino

FORMULA

G.f.: See Maple program.

MAPLE

gf:= -(x^21 +x^18 -2*x^15 -3*x^14 -2*x^12 -2*x^11 +x^9 +2*x^8 +3*x^7 +x^6 +x^5 +x^4-1) *(x-1)^6 *(x^6+x^5+x^4+x^3+x^2+x+1)^6 / (x^70 +x^67 -3*x^64 -10*x^63 -3*x^61 -9*x^60 +3*x^58 +23*x^57 +45*x^56 +3*x^55 +21*x^54 +36*x^53 -x^52 -19*x^51 -76*x^50 -121*x^49 -18*x^48 -63*x^47 -84*x^46 +6*x^45 +51*x^44 +140*x^43 +216*x^42 +45*x^41 +105*x^40 +126*x^39

-15*x^38 -75*x^37 -154*x^36 -267*x^35 -60*x^34 -105*x^33 -126*x^32 +20*x^31 +65*x^30 +98*x^29 +236*x^28 +45*x^27 +63*x^26 +90*x^25 -15*x^24 -33*x^23 -40*x^22 -153*x^21 -18*x^20 -33*x^19 -48*x^18 +6*x^17 +15*x^16 +8*x^15 +69*x^14 +9*x^13 +9*x^12 +15*x^11 -x^10 -x^9 +5*x^8 -17*x^7 -x^4 -x +1):

a:= n-> coeff(series(gf, x, n+1), x, n):

seq(a(n), n=0..50);

CROSSREFS

Column k=7 of A250662.

Cf. A251076.

Sequence in context: A072806 A189402 A051942 * A082581 A075846 A164714

Adjacent sequences:  A250661 A250662 A250663 * A250665 A250666 A250667

KEYWORD

nonn,easy

AUTHOR

Alois P. Heinz, Nov 26 2014

STATUS

approved

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Last modified July 22 07:23 EDT 2019. Contains 325216 sequences. (Running on oeis4.)