A363810
Number of permutations of [n] that avoid the patterns 2-41-3, 3-14-2, 2-14-3, and 4-5-3-1-2.
Original entry on oeis.org
1, 1, 2, 6, 21, 79, 306, 1196, 4681, 18308, 71564, 279820, 1095533, 4298463, 16913428, 66769536, 264526329, 1051845461, 4197832133, 16813161765, 67571221016, 272448598737, 1101876945673, 4469106749281, 18174503562880, 74093063050412, 302753929958872
Offset: 0
Other entries including the patterns 1, 2, 3, 4 in the Merino and Mütze reference:
A006318,
A106228,
A363809,
A078482,
A033321,
A363811,
A363812,
A363813,
A006012.
-
with(gfun): seq(coeff(algeqtoseries(x^8*(-2+x)^2*F^4 - x^3*(x-1)*(-2+x)*(x^5-7*x^4+4*x^3-6*x^2+5*x-1)*F^3 - x*(x-1)*(4*x^7-22*x^6+37*x^5-42*x^4+53*x^3-35*x^2+10*x-1)*F^2 - (5*x^6-16*x^5+15*x^4-28*x^3+23*x^2-8*x+1)*(x-1)^2*F - (2*x^5-5*x^4+4*x^3-10*x^2+6*x-1)*(x-1)^2, x, F, 32, true)[1], x, n+1), n = 0..30); # Vaclav Kotesovec, Jun 24 2023
A363811
Number of permutations of [n] that avoid the patterns 2-41-3, 3-14-2, 2-1-3-5-4, and 4-5-3-1-2.
Original entry on oeis.org
1, 1, 2, 6, 22, 88, 362, 1488, 6034, 24024, 93830, 359824, 1357088, 5043260, 18501562, 67120024, 241169322, 859450004, 3041415520, 10699090888, 37448249502, 130518538696, 453276141238, 1569476495000, 5420784841936, 18683861676756, 64286814548706
Offset: 0
- Andrei Asinowski and Cyril Banderier, From geometry to generating functions: rectangulations and permutations, arXiv:2401.05558 [cs.DM], 2024. See page 2.
- Arturo Merino and Torsten Mütze. Combinatorial generation via permutation languages. III. Rectangulations. Discrete & Computational Geometry, 70 (2023), 51-122. Preprint: arXiv:2103.09333 [math.CO], 2021.
- Index entries for linear recurrences with constant coefficients, signature (18,-141,630,-1767,3224,-3834,2896,-1312,320,-32).
Other entries including the patterns 1, 2, 3, 4 in the Merino and Mütze reference:
A006318,
A106228,
A363809,
A078482,
A033321,
A363810,
A363812,
A363813,
A006012.
-
CoefficientList[Series[(1 - x)*(1 - 16*x + 109*x^2 - 410*x^3 + 923*x^4 - 1256*x^5 + 988*x^6 - 400*x^7 + 66*x^8 - 2*x^9)/((1 - 4*x + 2*x^2)*(1 - 3*x + x^2)^2*(1 - 2*x)^4),{x,0,26}],x] (* Stefano Spezia, Jun 24 2023 *)
A363812
Number of permutations of [n] that avoid the patterns 2-41-3, 3-14-2, 2-1-4-3, and 3-41-2.
Original entry on oeis.org
1, 1, 2, 6, 20, 69, 243, 870, 3159, 11611, 43130, 161691, 611065, 2325739, 8907360, 34304298, 132770564, 516164832, 2014739748, 7892775473, 31022627947, 122304167437, 483513636064, 1916394053725, 7613498804405, 30313164090695
Offset: 0
Other entries including the patterns 1, 2, 3, 4 in the Merino and Mütze reference:
A006318,
A106228,
A363809,
A078482,
A033321,
A363810,
A363811,
A363813,
A006012.
-
CoefficientList[Series[(1 - 3*x + 3*x^2 - Sqrt[1 - 6*x + 7*x^2 + 2*x^3 + x^4])/(2*x^2*(2 - x)),{x,0,25}],x] (* Stefano Spezia, Jun 24 2023 *)
A363813
Number of permutations of [n] that avoid the patterns 2-41-3, 3-14-2, 2-1-4-3, and 4-5-3-1-2.
Original entry on oeis.org
1, 1, 2, 6, 21, 78, 295, 1114, 4166, 15390, 56167, 202738, 724813, 2570276, 9052494, 31702340, 110503497, 383691578, 1328039043, 4584708230, 15793983638, 54315199642, 186526735307, 639831906594, 2192754259993, 7509139583560, 25699765092254, 87913948206096
Offset: 0
- Andrei Asinowski and Cyril Banderier, From geometry to generating functions: rectangulations and permutations, arXiv:2401.05558 [cs.DM], 2024. See page 2.
- Arturo Merino and Torsten Mütze. Combinatorial generation via permutation languages. III. Rectangulations. Discrete & Computational Geometry, 70 (2023), 51-122. Preprint: arXiv:2103.09333 [math.CO], 2021.
- Index entries for linear recurrences with constant coefficients, signature (10,-37,62,-47,16,-2).
Other entries including the patterns 1, 2, 3, 4 in the Merino and Mütze reference:
A006318,
A106228,
A363809,
A078482,
A033321,
A363810,
A363811,
A363812,
A006012.
-
CoefficientList[Series[(1 - 9*x + 29*x^2 - 39*x^3 + 20*x^4 - 3*x^5)/((1 - 4*x + 2*x^2)*(1 - 3*x + x^2)^2),{x,0,27}],x] (* Stefano Spezia, Jun 24 2023 *)
A129167
Number of base pyramids in all skew Dyck paths of semilength n.
Original entry on oeis.org
0, 1, 3, 9, 30, 109, 420, 1685, 6960, 29391, 126291, 550359, 2426502, 10803801, 48507843, 219377949, 998436792, 4569488371, 21016589073, 97090411019, 450314942682, 2096122733211, 9788916220518, 45850711498859, 215348942668680, 1013979873542689, 4785437476592805, 22633143884165985, 107258646298581390
Offset: 0
a(2)=3 because in the paths (UD)(UD), (UUDD) and UUDL we have altogether 3 base pyramids (shown between parentheses).
-
G:=(1-3*z-sqrt(1-6*z+5*z^2))/z/(3-3*z-sqrt(1-6*z+5*z^2)): Gser:=series(G,z=0,30): seq(coeff(Gser,z,n),n=0..27);
-
CoefficientList[Series[(1-3*x-Sqrt[1-6*x+5*x^2])/(x*(3-3*x-Sqrt[1-6*x+5*x^2])), {x, 0, 20}], x] (* Vaclav Kotesovec, Oct 20 2012 *)
-
z='z+O('z^66); concat([0], Vec((1-3*z-sqrt(1-6*z+5*z^2))/z/(3-3*z-sqrt(1-6*z+5*z^2)))) \\ Joerg Arndt, Aug 27 2014
A171224
Riordan array (f(x),x*f(x)) where f(x) is the g.f. of A117641.
Original entry on oeis.org
1, 0, 1, 1, 0, 1, 3, 2, 0, 1, 11, 6, 3, 0, 1, 42, 23, 9, 4, 0, 1, 167, 90, 36, 12, 5, 0, 1, 684, 365, 144, 50, 15, 6, 0, 1, 2867, 1518, 595, 204, 65, 18, 7, 0, 1, 12240, 6441, 2511, 858, 270, 81, 21, 8, 0, 1, 53043, 27774, 10782, 3672, 1155, 342, 98, 24, 9, 0, 1
Offset: 0
Triangle begins
1;
0, 1;
1, 0, 1;
3, 2, 0, 1;
11, 6, 3, 0, 1;
42, 23, 9, 4, 0, 1;
167, 90, 36, 12, 5, 0, 1;
...
Production array begins
0, 1;
1, 0, 1;
3, 1, 0, 1;
9, 3, 1, 0, 1;
27, 9, 3, 1, 0, 1;
81, 27, 9, 3, 1, 0, 1;
243, 81, 27, 9, 3, 1, 0, 1;
... - _Philippe Deléham_, Mar 04 2013
-
[[((k+1)/(n+1))*(&+[3^(n-k-2*j)*Binomial(n+1,j)*Binomial(n-k-j-1, n-k-2*j): j in [0..Floor((n-k)/2)]]): k in [0..n]]: n in [0..10]]; // G. C. Greubel, Apr 04 2019
-
T[n_, k_]:= (k+1)/(n+1)*Sum[3^(n-k-2*j)*Binomial[n+1,j]*Binomial[n-k-j-1, n-k-2*j], {j, 0, Floor[(n-k)/2]}]; Table[T[n, k], {n,0,10}, {k,0,n} ]//Flatten (* G. C. Greubel, Apr 04 2019 *)
-
T(n,k):=(k+1)/(n+1)*sum(3^(n-k-2*j)*binomial(n+1,j)*binomial(n-k-j-1,n-k-2*j),j,0,floor((n-k)/2)); /* Vladimir Kruchinin, Apr 04 2019 */
-
{T(n,k) = ((k+1)/(n+1))*sum(j=0, floor((n-k)/2), 3^(n-k-2*j) *binomial(n+1,j)*binomial(n-k-j-1, n-k-2*j))}; \\ G. C. Greubel, Apr 04 2019
-
[[((k+1)/(n+1))*sum(3^(n-k-2*j)*binomial(n+1,j)*binomial(n-k-j-1, n-k-2*j) for j in (0..floor((n-k)/2))) for k in (0..n)] for n in (0..10)] # G. C. Greubel, Apr 04 2019
A154930
Inverse of Fibonacci convolution array A154929.
Original entry on oeis.org
1, -2, 1, 5, -4, 1, -15, 14, -6, 1, 51, -50, 27, -8, 1, -188, 187, -113, 44, -10, 1, 731, -730, 468, -212, 65, -12, 1, -2950, 2949, -1956, 970, -355, 90, -14, 1, 12235, -12234, 8291, -4356, 1785, -550, 119, -16, 1, -51822, 51821, -35643, 19474, -8612, 3021
Offset: 0
Triangle begins
1,
-2, 1,
5, -4, 1,
-15, 14, -6, 1,
51, -50, 27, -8, 1,
-188, 187, -113, 44, -10, 1,
731, -730, 468, -212, 65, -12, 1,
-2950, 2949, -1956, 970, -355, 90, -14, 1
Production array is
-2, 1,
1, -2, 1,
-1, 1, -2, 1,
1, -1, 1, -2, 1,
-1, 1, -1, 1, -2, 1,
1, -1, 1, -1, 1, -2, 1,
-1, 1, -1, 1, -1, 1, -2, 1
or ((1-x-x^2)/(1+x),x) beheaded.
A171380
Expansion of the first column of triangle T_(1,x), T(x,y) defined in A039599; T_(1,0)= A061554, T_(1,1)= A064189, T_(1,2)= A039599, T_(1,3)= A110877, T_(1,4)= A124576.
Original entry on oeis.org
1, 1, 0, 2, 0, 0, 3, 1, 0, 0, 6, 2, 1, 0, 0, 10, 8, 2, 1, 0, 0, 20, 16, 12, 2, 1, 0, 0, 35, 47, 25, 17, 2, 1, 0, 0, 70, 94, 97, 36, 23, 2, 1, 0, 0, 126, 244, 204, 179, 49, 30, 2, 1, 0, 0
Offset: 0
Triangle begins:
1;
1, 0;
2, 0, 0;
3, 1, 0, 0;
6, 2, 1, 0, 0;
10, 8, 2, 1, 0, 0;
...
A278301
Number of permutations of length n in the class of juxtapositions of 321-avoiders with 21-avoiders.
Original entry on oeis.org
1, 1, 2, 6, 23, 98, 434, 1949, 8803, 39888, 181201, 825201, 3767757, 17249560, 79191480, 364585230, 1683208515, 7792546040, 36174065285, 168367375735, 785637327745, 3674914227120, 17230132657815, 80965662243526, 381275131584373, 1799105397745998
Offset: 0
There are 23 permutations of length 4 which can be expressed as a juxtaposition of a 321-avoider and a 21-avoider. Only 4321 is not expressable this way.
- G. C. Greubel, Table of n, a(n) for n = 0..1000
- Robert Brignall, Jakub Sliacan, Juxtaposing Catalan permutation classes with monotone ones, arXiv:1611.05370 [math.CO], 2016.
- Robert Brignall, Jakub Sliacan, Combinatorial specifications for juxtapositions of permutation classes, arXiv:1902.02705 [math.CO], 2019.
The other two juxtapositions of Catalan and monotone classes are enumerated by
A033321,
A165538.
-
e = ee /. Solve[ee == 1 + x/(1 - x) ee, ee][[1]];
c = cc /. Solve[cc == 1 + x cc^2, cc][[1]];
cb = ccb /. Solve[ccb == 1 + x/(1 - x) ccb^2, ccb][[2]];
b = bb /. Solve[bb == x^2/(1 - x) + x c bb e, bb][[1]];
m = mm /.
Solve[mm ==
x c mm cb + b e x/(1 - x) (cb - 1) + x^2/(1 - x) (cb - 1),
mm][[1]];
f = c + c m cb/(1 - x);
CoefficientList[Series[f, {x, 0, 25}], x]
Rest[CoefficientList[Series[(1 - (1 - 4 x)^(1/2) + x (-4 + (1 - 4 x)^(1/2) + ((-1 + 5 x)^(1/2)) / ((-1 + x)^(1/2))))/ (-2 x^2), {x, 0, 33}], x]] (* Vincenzo Librandi, Nov 18 2016 *)
A128722
Triangle read by rows: T(n,k) is the number of skew Dyck paths of semilength n and having k hills (i.e., peaks at level 1) (0 <= k <= n).
Original entry on oeis.org
1, 0, 1, 2, 0, 1, 6, 3, 0, 1, 22, 9, 4, 0, 1, 84, 35, 12, 5, 0, 1, 334, 138, 49, 15, 6, 0, 1, 1368, 563, 198, 64, 18, 7, 0, 1, 5734, 2352, 825, 264, 80, 21, 8, 0, 1, 24480, 10015, 3504, 1121, 336, 97, 24, 9, 0, 1, 106086, 43308, 15123, 4833, 1452, 414, 115, 27, 10, 0, 1
Offset: 0
T(3,1)=3 because we have (UD)UUDD, (UD)UUDL and UUDD(UD) (the hills are shown between parentheses).
Triangle starts:
1;
0, 1;
2, 0, 1;
6, 3, 0, 1;
22, 9, 4, 0, 1;
84, 35, 12, 5, 0, 1;
- E. Deutsch, E. Munarini, S. Rinaldi, Skew Dyck paths, J. Stat. Plann. Infer. 140 (8) (2010) 2191-2203
-
g:=(1-z-sqrt(1-6*z+5*z^2))/2/z: G:=(1-z+z*g)/(1+z-z*g-t*z): Gser:=simplify(series(G,z=0,14)): for n from 0 to 12 do P[n]:=sort(coeff(Gser,z,n)) od: for n from 0 to 11 do seq(coeff(P[n],t,j),j=0..n) od; # yields sequence in triangular form
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