A250662
Number A(n,k) of tilings of a 2k X n rectangle using 2n k-ominoes of shape I; square array A(n,k), n>=0, k>=0, read by antidiagonals.
Original entry on oeis.org
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 5, 1, 1, 1, 1, 1, 11, 1, 1, 1, 1, 1, 6, 36, 1, 1, 1, 1, 1, 1, 13, 95, 1, 1, 1, 1, 1, 1, 7, 22, 281, 1, 1, 1, 1, 1, 1, 1, 15, 64, 781, 1, 1, 1, 1, 1, 1, 1, 8, 25, 155, 2245, 1, 1, 1, 1, 1, 1, 1, 1, 17, 37, 321, 6336, 1, 1
Offset: 0
Square array A(n,k) begins:
1, 1, 1, 1, 1, 1, 1, 1, 1, ...
1, 1, 1, 1, 1, 1, 1, 1, 1, ...
1, 1, 5, 1, 1, 1, 1, 1, 1, ...
1, 1, 11, 6, 1, 1, 1, 1, 1, ...
1, 1, 36, 13, 7, 1, 1, 1, 1, ...
1, 1, 95, 22, 15, 8, 1, 1, 1, ...
1, 1, 281, 64, 25, 17, 9, 1, 1, ...
1, 1, 781, 155, 37, 28, 19, 10, 1, ...
1, 1, 2245, 321, 100, 41, 31, 21, 11, ...
Columns k=0+1,2-10 give:
A000012,
A005178(n+1),
A236577,
A236582,
A247117,
A250663,
A250664,
A250665,
A250666,
A250667.
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b:= proc(n, l) option remember; local d, k; d:= nops(l)/2;
if n=0 then 1
elif min(l[])>0 then (m->b(n-m, map(x->x-m, l)))(min(l[]))
else for k while l[k]>0 do od;
`if`(nd+1 or max(l[k..k+d-1][])>0, 0,
b(n, [l[1..k-1][],1$d,l[k+d..2*d][]]))
fi
end:
A:= (n, k)-> `if`(k=0, 1, b(n, [0$2*k])):
seq(seq(A(n,d-n), n=0..d), d=0..14);
-
b[n_, l_List] := b[n, l] = Module[{d = Length[l]/2, k}, Which[n == 0, 1, Min[l] > 0 , Function[{m}, b[n-m, l-m]][Min[l]], True, For[k=1, l[[k]] > 0, k++]; If[n d]]] + If[d == 1 || k > d+1 || Max[l[[k ;; k+d-1]]] > 0, 0, b[n, Join[l[[1 ;; k-1]], Array[1&, d], l[[k+d ;; 2*d]]]]]]]; A[n_, k_] := If[k == 0, 1, b[n, Array[0&, 2k]]]; Table[Table[A[n, d-n], {n, 0, d}], {d, 0, 14}] // Flatten (* Jean-François Alcover, Jan 30 2015, after Alois P. Heinz *)
A028468
Number of perfect matchings in graph P_{6} X P_{n}.
Original entry on oeis.org
1, 1, 13, 41, 281, 1183, 6728, 31529, 167089, 817991, 4213133, 21001799, 106912793, 536948224, 2720246633, 13704300553, 69289288909, 349519610713, 1765722581057, 8911652846951, 45005025662792, 227191499132401, 1147185247901449, 5791672851807479
Offset: 0
- F. Faase, On the number of specific spanning subgraphs of the graphs G X P_n, Ars Combin. 49 (1998), 129-154.
- R. P. Stanley, Enumerative Combinatorics I, p. 292.
- Alois P. Heinz, Table of n, a(n) for n = 0..450
- F. Faase, On the number of specific spanning subgraphs of the graphs G X P_n, Preliminary version of paper that appeared in Ars Combin. 49 (1998), 129-154.
- F. Faase, Counting Hamiltonian cycles in product graphs
- F. Faase, Results from the counting program
- David Klarner and Jordan Pollack, Domino tilings of rectangles with fixed width, Disc. Math. 32 (1980) 45-52.
- Per Hakan Lundow, Computation of matching polynomials and the number of 1-factors in polygraphs, Research report, No 12, 1996, Department of Math., Umea University, Sweden.
- Per Hakan Lundow, Enumeration of matchings in polygraphs, 1998.
- R. J. Mathar, Paving rectangular regions with rectangular tiles: tatami and non-tatami tilings, arXiv:1311.6135 [math.CO], 2013, Table 5.
- Thotsaporn "Aek" Thanatipanonda, Statistics of Domino Tilings on a Rectangular Board, Fibonacci Quart. 57 (2019), no. 5, 145-153. See p. 151.
- Index entries for linear recurrences with constant coefficients, signature (1,20,10,-38,-10,20,-1,-1).
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m:=30; R:=PowerSeriesRing(Integers(), m); Coefficients(R!( (x^2-2*x-1)*(x^4+2*x^3-3*x^2-2*x+1)/((1-x^2)*(x^3-5*x^2+6*x-1)*(x^3+ 6*x^2+5*x+1)) )); // G. C. Greubel, Nov 25 2018
-
seq(coeff(series((1+2*x-x^2)*(x^4+2*x^3-3*x^2-2*x+1)/((x-1)*(x+1)*(x^3-5*x^2+6*x-1)*(x^3+6*x^2+5*x+1)),x,n+1), x, n), n = 0 .. 25); # Muniru A Asiru, Nov 23 2018
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a[n_] := Product[2(2 + Cos[(2 k Pi)/7] + Cos[(2 j Pi)/(n+1)]), {k, 1, 3}, {j, 1, n/2}] // Round;
Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Aug 19 2018, after A099390 *)
LinearRecurrence[{1, 20, 10, -38, -10, 20, -1, -1}, {1, 1, 13, 41, 281, 1183, 6728, 31529}, 30] (* Vincenzo Librandi, Nov 24 2018 *)
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my(x='x+O('x^30)); Vec(-(x^2-2*x-1)*(x^4+2*x^3-3*x^2-2*x+1)/((x-1)*(1+x)*(x^3-5*x^2+6*x-1)*(x^3+6*x^2+5*x+1))) \\ Altug Alkan, Mar 23 2016
-
s=((x^2-2*x-1)*(x^4+2*x^3-3*x^2-2*x+1)/((1-x^2)*(x^3-5*x^2+6*x-1) *(x^3+6*x^2+5*x+1))).series(x,30); s.coefficients(x, sparse=False) # G. C. Greubel, Nov 25 2018
A251074
Number of tilings of a 12 X n rectangle using 3n tetrominoes of shape I.
Original entry on oeis.org
1, 1, 1, 1, 26, 75, 154, 269, 1732, 5764, 15131, 34345, 135950, 462186, 1356284, 3539433, 11681091, 38519022, 118366429, 334591568, 1037603086, 3309045401, 10296063522, 30414763937, 92735958046, 289374852696, 899439481823, 2716896548850, 8270384213984
Offset: 0
A247218
Number of tilings of a 15 X n rectangle using 3n pentominoes of shape I.
Original entry on oeis.org
1, 1, 1, 1, 1, 34, 95, 190, 325, 506, 3324, 10353, 25607, 55346, 108756, 389216, 1208901, 3281686, 8006108, 17950204, 51430928, 150609259, 419540401, 1090827453, 2651884943, 7077981621, 19691707908, 54499735145, 145671654672, 371632691473, 976543067070
Offset: 0
A251073
Number of tilings of a 9 X n rectangle using 3n trominoes of shape I.
Original entry on oeis.org
1, 1, 1, 19, 57, 121, 783, 2861, 8133, 37160, 143419, 468816, 1876855, 7263468, 25496863, 97187247, 372086645, 1352780401, 5071962134, 19220628318, 71025008365, 265095817718, 997839772024, 3713274525679, 13851695644227, 51940567251136, 193830054345968
Offset: 0
A251075
Number of tilings of a 18 X n rectangle using 3n hexominoes of shape I.
Original entry on oeis.org
1, 1, 1, 1, 1, 1, 43, 117, 229, 385, 591, 853, 5789, 17163, 40521, 84211, 160143, 284639, 945352, 2743255, 7017326, 16250983, 34801374, 69959957, 179843441, 479965811, 1238082783, 3015746329, 6925030997, 15065972891, 35869626723, 89673470947, 226122534275
Offset: 0
A251076
Number of tilings of a 21 X n rectangle using 3n heptominoes of shape I.
Original entry on oeis.org
1, 1, 1, 1, 1, 1, 1, 53, 141, 271, 449, 681, 973, 1331, 9391, 26803, 60953, 122641, 226921, 394031, 650413, 2039288, 5611209, 13694084, 30417897, 62763334, 122046063, 225958222, 532867801, 1319078776, 3196149101, 7383041514, 16186545853, 33788903208
Offset: 0
A251077
Number of tilings of a 24 X n rectangle using 3n octominoes of shape I.
Original entry on oeis.org
1, 1, 1, 1, 1, 1, 1, 1, 64, 167, 316, 517, 776, 1099, 1492, 1961, 14428, 39956, 88103, 172509, 311816, 530678, 860861, 1342433, 4020710, 10599604, 24896626, 53438385, 106915866, 202198270, 365048944, 633709553, 1392777233, 3238633334, 7446642085, 16454751188
Offset: 0
A251078
Number of tilings of a 27 X n rectangle using 3n nonominoes of shape I.
Original entry on oeis.org
1, 1, 1, 1, 1, 1, 1, 1, 1, 76, 195, 364, 589, 876, 1231, 1660, 2169, 2764, 21232, 57379, 123291, 235860, 417784, 698657, 1116149, 1717276, 2559760, 7386240, 18797731, 42769684, 89201688, 173879976, 321141337, 567405676, 965768880, 1591873744, 3298800992
Offset: 0
A251079
Number of tilings of a 30 X n rectangle using 3n decominoes of shape I.
Original entry on oeis.org
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 89, 225, 415, 665, 981, 1369, 1835, 2385, 3025, 3761, 30169, 79903, 167957, 314911, 548011, 902339, 1422073, 2161837, 3188141, 4580911, 12815576, 31665861, 70135406, 142741143, 272097694, 492367347, 853768306, 1428360119
Offset: 0
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