cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-10 of 12 results. Next

A264173 Number T(n,k) of permutations of [n] with exactly k (possibly overlapping) occurrences of the consecutive pattern 1324; triangle T(n,k), n>=0, 0<=k<=max(0,floor(n/2-1)), read by rows.

Original entry on oeis.org

1, 1, 2, 6, 23, 1, 110, 10, 632, 86, 2, 4229, 782, 29, 32337, 7571, 407, 5, 278204, 78726, 5856, 94, 2659223, 882997, 84351, 2215, 14, 27959880, 10657118, 1251246, 48234, 322, 320706444, 137977980, 19318314, 984498, 14322, 42, 3985116699, 1910131680, 311306106
Offset: 0

Views

Author

Alois P. Heinz, Nov 06 2015

Keywords

Comments

Pattern 4231 gives the same triangle.

Examples

			T(4,1) = 1: 1324.
T(6,2) = 2: 132546, 142536.
T(8,3) = 5: 13254768, 13264758, 14253768, 14263758, 15263748.
T(10,4) = 14: 132547698(10), 132548697(10), 132647598(10), 132648597(10), 132748596(10), 142537698(10), 142538697(10), 142637598(10), 142638597(10), 142738596(10), 152637498(10), 152638497(10), 152738496(10), 162738495(10).
Triangle T(n,k) begins:
00 :        1;
01 :        1;
02 :        2;
03 :        6;
04 :       23,      1;
05 :      110,     10;
06 :      632,     86,     2;
07 :     4229,    782,    29;
08 :    32337,   7571,   407,    5;
09 :   278204,  78726,  5856,   94;
10 :  2659223, 882997, 84351, 2215, 14;
		

Crossrefs

Row sums give A000142.
T(2n+2,n) gives A000108(n) for n>0.
Cf. A004526, A061206, A264319 (pattern 3412).

Programs

  • Maple
    b:= proc(u, o, t) option remember; expand(`if`(u+o=0, 1,
          add(b(u-j, o+j-1, `if`(t>0 and j (p-> seq(coeff(p, x, i), i=0..degree(p)))(b(n, 0$2)):
    seq(T(n), n=0..14);
  • Mathematica
    b[u_, o_, t_] := b[u, o, t] = Expand[If[u + o == 0, 1, Sum[b[u - j, o + j - 1, If[t > 0 && j < t, -j, 0]], {j, 1, u}] + Sum[b[u + j - 1, o - j, j] * If[t < 0 && -j <= t, x, 1], {j, 1, o}]]];
    T[n_] := Function[p, Table[Coefficient[p, x, i], {i, 0, Exponent[p, x]}]][ b[n, 0, 0]];
    Table[T[n], {n, 0, 14}] // Flatten (* Jean-François Alcover, Apr 30 2017, translated from Maple *)

Formula

Sum_{k>0} k * T(n,k) = ceiling((n-3)*n!/4!) = A061206(n-3) (for n>3).

A113229 Number of permutations avoiding the consecutive pattern 3412.

Original entry on oeis.org

1, 1, 2, 6, 23, 110, 631, 4223, 32301, 277962, 2657797, 27954521, 320752991, 3987045780, 53372351265, 765499019221, 11711207065229, 190365226548070, 3276401870322033, 59523410471007913, 1138295039078030599, 22856576346825690128, 480807130959249565541
Offset: 0

Views

Author

David Callan, Oct 19 2005

Keywords

Comments

a(n) is the number of permutations on [n] that avoid the consecutive pattern 3412 (also number that avoid 2143).

Examples

			The 5! - a(5) = 10 permutations on [5] not counted by a(5) are 14523, 24513, 34125, 34512, 35124, 43512, 45123, 45132, 45231, 53412.
		

Crossrefs

Programs

  • Maple
    b:= proc(u, o, t) option remember; `if`(u+o=0, 1,
          add(b(u-j, o+j-1, `if`(t>0 and j>t, t-j, 0)), j=1..u)+
          add(b(u+j-1, o-j, j), j=`if`(t<0,1-t,1)..o))
        end:
    a:= n-> b(n, 0$2):
    seq(a(n), n=0..25);  # Alois P. Heinz, Nov 07 2013
  • Mathematica
    b[u_, o_, t_] := b[u, o, t] = If[u+o == 0, 1, Sum[b[u-j, o+j-1, If[t>0 && j>t, t-j, 0]], {j, 1, u}] + Sum[b[u+j-1, o-j, j], {j, Range[If[t<0, 1-t, 1], o]}]]; a[n_] := b[n, 0, 0]; Table[a[n], {n, 0, 25}] (* Jean-François Alcover, Mar 13 2015, after Alois P. Heinz *)

Formula

The Dotsenko et al. reference gives a g.f. There is an associated triangle of numbers c_{n,l} that should be added to the OEIS if it is not already present.
a(n) ~ c * d^n * n!, where d = 0.9561742431150784273897350385923872770208469..., c = 1.1465405299007850875068632404058971045769... . - Vaclav Kotesovec, Aug 23 2014

A264320 Number of permutations of [n] with exactly one occurrence of the consecutive pattern 3412.

Original entry on oeis.org

1, 10, 88, 794, 7639, 79164, 885128, 10657588, 137752283, 1904555934, 28068929900, 439495830750, 7288494061255, 127654030808304, 2355066281798588, 45655570757683888, 927984709909530539, 19735811069218548106, 438344811235148801632, 10149979837759608190794
Offset: 4

Views

Author

Alois P. Heinz, Nov 11 2015

Keywords

Examples

			a(4) = 1: 3412.
a(5) = 10: 14523, 24513, 34125, 34512, 35124, 43512, 45123, 45132, 45231, 53412.
		

Crossrefs

Column k=1 of A264319.

A264321 Number of permutations of [n] with exactly two (possibly overlapping) occurrences of the consecutive pattern 3412.

Original entry on oeis.org

1, 23, 379, 5706, 84354, 1266150, 19621124, 316459848, 5331647951, 93959680785, 1732274350449, 33392773007922, 672442070185276, 14130089667648160, 309458726679280550, 7054945428667834408, 167218369471952249237, 4115763361988379577315, 105071634182596234984655
Offset: 6

Views

Author

Alois P. Heinz, Nov 11 2015

Keywords

Examples

			a(6) = 1: 563412.
a(7) = 23: 1674523, 2674513, 3674512, 4673512, 5614723, 5624713, 5634127, 5634712, 5673412, 5714623, 5724613, 5734126, 5734612, 6573412, 6714523, 6724513, 6734125, 6734512, 6735124, 6745123, 6745132, 6745231, 7563412.
		

Crossrefs

Column k=2 of A264319.

A264322 Number of permutations of [n] with exactly three (possibly overlapping) occurrences of the consecutive pattern 3412.

Original entry on oeis.org

1, 48, 1520, 38452, 869740, 18720732, 396975296, 8458711900, 183197270195, 4060222577980, 92457026432364, 2168229942019192, 52433345808131318, 1308330112118893072, 33691149632085370112, 895280698879996177240, 24542614402374373350957, 693775997089974201665016
Offset: 8

Views

Author

Alois P. Heinz, Nov 11 2015

Keywords

Examples

			a(8) = 1: 78563412.
a(9) = 48: 189674523, 289674513, 389674512, ..., 896745132, 896745231, 978563412.
		

Crossrefs

Column k=3 of A264319.

A264323 Number of permutations of [n] with exactly four (possibly overlapping) occurrences of the consecutive pattern 3412.

Original entry on oeis.org

1, 89, 5461, 238356, 8368831, 259770975, 7542478135, 211794493290, 5870838954710, 162745118970610, 4549825111681964, 128994813976541176, 3722621639161251074, 109622707753571938234, 3299453321046315967098, 101610430484526744949716, 3203896974449174366163207
Offset: 10

Views

Author

Alois P. Heinz, Nov 11 2015

Keywords

Crossrefs

Column k=4 of A264319.

A264324 Number of permutations of [n] with exactly five (possibly overlapping) occurrences of the consecutive pattern 3412.

Original entry on oeis.org

1, 150, 17956, 1354134, 74605701, 3373438200, 134999600212, 5013535378432, 178086394182356, 6171760208699812, 211481116147026848, 7230935446550288908, 248287682074519332846, 8600459778995519305416, 301511114563838537243472, 10722994509016940787519096
Offset: 12

Views

Author

Alois P. Heinz, Nov 11 2015

Keywords

Crossrefs

Column k=5 of A264319.

A264325 Number of permutations of [n] with exactly six (possibly overlapping) occurrences of the consecutive pattern 3412.

Original entry on oeis.org

1, 235, 57035, 7221886, 618249852, 40878791512, 2270356257626, 112176122124184, 5127825571576298, 222748847168538286, 9366990120105399606, 386330492305650221364, 15774418153169702657988, 642000537768645881284284, 26174608034919642252229176
Offset: 14

Views

Author

Alois P. Heinz, Nov 11 2015

Keywords

Crossrefs

Column k=6 of A264319.

A264326 Number of permutations of [n] with exactly seven (possibly overlapping) occurrences of the consecutive pattern 3412.

Original entry on oeis.org

1, 348, 184964, 37331800, 4838911370, 464380098592, 35861849944448, 2368950978884920, 140048359125251970, 7656366194099685024, 396295578652586265936, 19754556228617612401848, 960237883152840490862664, 45936904818881537730689976, 2177814852070869127205627616
Offset: 16

Views

Author

Alois P. Heinz, Nov 11 2015

Keywords

Crossrefs

Column k=7 of A264319.

A264327 Number of permutations of [n] with exactly eight (possibly overlapping) occurrences of the consecutive pattern 3412.

Original entry on oeis.org

1, 493, 633677, 191009848, 36439591193, 5004015747625, 534739648790073, 47271093160982634, 3626506774076237883, 250491072534377023959, 16015467370198042469229, 967671571943986351197684, 56117598468254134348216611, 3160386391272010574690621055
Offset: 18

Views

Author

Alois P. Heinz, Nov 11 2015

Keywords

Crossrefs

Column k=8 of A264319.
Showing 1-10 of 12 results. Next