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 23 results. Next

A202213 Number of permutations of [n] avoiding the consecutive pattern 45321.

Original entry on oeis.org

1, 1, 2, 6, 24, 119, 708, 4914, 38976, 347765, 3447712, 37598286, 447294144, 5764747515, 80011430240, 1189835682714, 18873422539776, 318085061976105, 5676223254661760, 106919460527212950, 2119973556022047744, 44136046410218669055, 962630898723772565760
Offset: 0

Views

Author

Ray Chandler, Dec 14 2011

Keywords

Comments

a(n) is the number of permutations on [n] that avoid the consecutive pattern 45321. It is the same as the number of permutations which avoid 12354, 21345 or 54312.

Crossrefs

Column k = 0 of A264781 and row m = 2 of A327722.

Programs

  • Maple
    b:= proc(u, o, t) option remember; `if`(u+o=0, 1,
          add(b(u+j-1, o-j, `if`(u+j-10, -1, `if`(t=-1, -2, 0)))), j=1..u)))
        end:
    a:= n-> b(n, 0$2):
    seq(a(n), n=0..40);  # Alois P. Heinz, Nov 19 2013
  • Mathematica
    b[u_, o_, t_] := b[u, o, t] = If[u+o == 0, 1, Sum[b[u+j-1, o-j, If[u+j-1 < j, 0, j]], {j, 1, o}] + If[t == -2, 0, Sum[b[u-j, o+j-1, If[j0, -1, If[t == -1, -2, 0]]]], {j, 1, u}]]]; a[n_] := b[n, 0, 0]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Mar 12 2015, after Alois P. Heinz *)

Formula

From Petros Hadjicostas, Nov 02 2019: (Start)
E.g.f.: 1/W(z), where W(z) = 1 + Sum_{n >= 0} (-1)^(n+1)* z^(4*n+1)/(b(n)*(4*n+1)) with b(n) = A329070(n,4) = (4*n)!/(4^n*(1/4)_n). (Here (x)_n = x*(x + 1)*...*(x + n - 1) is the Pochhammer symbol, or rising factorial, which is denoted by (x)^n in some papers and books.) The function W(z) satisfies the o.d.e. W^(4)(z) + z*W'(z) = 0 with W(0) = 1, W'(0) = -1, and W^(k)(0) = 0 for k = 2..3. [See Theorem 3.2 (with m = a = 3 and u = 0) in Elizalde and Noy (2003).]
a(n) = Sum_{m = 0..floor((n-1)/4)} (-4)^m * (1/4)_m * binomial(n, 4*m+1) * a(n-4*m-1) for n >= 1 with a(0) = 1. (End)

A202214 Number of permutations avoiding the consecutive pattern 53421.

Original entry on oeis.org

1, 2, 6, 24, 119, 708, 4914, 38977, 347779, 3447902, 37600925, 447332398, 5765327905, 80020698913, 1189991560707, 18876181370841, 318136382176708, 5677225148401090, 106939954137362482, 2120412050923152077, 44145844897844974946, 962859209130749461268
Offset: 1

Views

Author

Ray Chandler, Dec 14 2011

Keywords

Comments

a(n) is the number of permutations on [n] that avoid the consecutive pattern 53421. It is the same as the number of permutations which avoid 12435, 13245 or 54231.

Crossrefs

A202235 Number of permutations avoiding the consecutive pattern 32415.

Original entry on oeis.org

1, 2, 6, 24, 119, 708, 4915, 38992, 347990, 3450772, 37640794, 447908832, 5774077131, 80160465380, 1192342710241, 18917802834912, 318910800658728, 5692346715440768, 107249322475436984, 2127032690422975168, 44293813329642772714, 966307529386769800328
Offset: 1

Views

Author

Ray Chandler, Dec 15 2011

Keywords

Comments

a(n) is the number of permutations on [n] that avoid the consecutive pattern 32415. It is the same as the number of permutations which avoid 15243, 34251 or 51423.

Crossrefs

A202215 Number of permutations avoiding the consecutive pattern 43251.

Original entry on oeis.org

1, 2, 6, 24, 119, 708, 4914, 38977, 347783, 3447982, 37602245, 447353497, 5765670515, 80026435959, 1190091483826, 18877998176267, 318170909582504, 5677911026433716, 106954187252974515, 2120720309936327198, 44152804913927293967, 963022839743497051427
Offset: 1

Views

Author

Ray Chandler, Dec 14 2011

Keywords

Comments

a(n) is the number of permutations on [n] that avoid the consecutive pattern 43251. It is the same as the number of permutations which avoid 15234, 23415 or 51432.

Crossrefs

A202216 Number of permutations avoiding the consecutive pattern 34521.

Original entry on oeis.org

1, 2, 6, 24, 119, 708, 4914, 38976, 347775, 3447912, 37601586, 447346944, 5765604885, 80025786960, 1190085736014, 18877969022976, 318171464604945, 5677939605422880, 106955077375109430, 2120744934976978944, 44153462828412744975, 963040357207773472320
Offset: 1

Views

Author

Ray Chandler, Dec 14 2011

Keywords

Comments

a(n) is the number of permutations on [n] that avoid the consecutive pattern 34521. It is the same as the number of permutations which avoid 12453, 31245, 35421, 54213, 12543, 32145 or 54123.

Crossrefs

A202217 Number of permutations avoiding the consecutive pattern 45132.

Original entry on oeis.org

1, 2, 6, 24, 119, 708, 4914, 38976, 347776, 3447932, 37601916, 447352224, 5765690544, 80027220448, 1190110692204, 18878422622976, 318180082610048, 5678110761876224, 106958628519952128, 2120821833862388544, 44155198873515034560, 963081167548894179456
Offset: 1

Views

Author

Ray Chandler, Dec 14 2011

Keywords

Comments

a(n) is the number of permutations on [n] that avoid the consecutive pattern 45132. It is the same as the number of permutations which avoid 21534, 23154 or 43512.

Crossrefs

A202218 Number of permutations avoiding the consecutive pattern 32451.

Original entry on oeis.org

1, 2, 6, 24, 119, 708, 4914, 38977, 347793, 3448182, 37605545, 447406214, 5766525727, 80040747361, 1190340631290, 18882526564227, 318256944873984, 5679619717431613, 106989639176572571, 2121488012937187849, 44170136425049025574, 963430265253564585315
Offset: 1

Views

Author

Ray Chandler, Dec 15 2011

Keywords

Comments

a(n) is the number of permutations on [n] that avoid the consecutive pattern 32451. It is the same as the number of permutations which avoid 15423, 34215 or 51243.

Crossrefs

A202219 Number of permutations avoiding the consecutive pattern 45312.

Original entry on oeis.org

1, 2, 6, 24, 119, 708, 4914, 38977, 347794, 3448202, 37605875, 447411544, 5766612686, 80042208149, 1190366133003, 18882991058982, 318265784348321, 5679795502722184, 106993290279989932, 2121567147336853153, 44171924298572910714, 963472321485580749448
Offset: 1

Views

Author

Ray Chandler, Dec 15 2011

Keywords

Comments

a(n) is the number of permutations on [n] that avoid the consecutive pattern 45312. It is the same as the number of permutations which avoid 21354.

Crossrefs

A202220 Number of permutations avoiding the consecutive pattern 53241.

Original entry on oeis.org

1, 2, 6, 24, 119, 708, 4914, 38979, 347815, 3448442, 37608834, 447450930, 5767170785, 80050654711, 1190502148797, 18885313699983, 318307710883720, 5680593325882836, 107009253612595865, 2121902210596869336, 44179286193550935095, 963641311893918317652
Offset: 1

Views

Author

Ray Chandler, Dec 15 2011

Keywords

Comments

a(n) is the number of permutations on [n] that avoid the consecutive pattern 53241. It is the same as the number of permutations which avoid 13425, 14235 or 53241.

Crossrefs

A202221 Number of permutations avoiding the consecutive pattern 41523.

Original entry on oeis.org

1, 2, 6, 24, 119, 708, 4914, 38976, 347790, 3448212, 37606536, 447426144, 5766888120, 80047243080, 1190459039364, 18884750846976, 318300264871440, 5680496863401840, 107008122578788800, 2121893387875882944, 44179385761361239200, 963649662245743556160
Offset: 1

Views

Author

Ray Chandler, Dec 15 2011

Keywords

Comments

a(n) is the number of permutations on [n] that avoid the consecutive pattern 41523. It is the same as the number of permutations which avoid 24153, 31524, 35142, 42513, 25143, 32514 or 34152.

Crossrefs

Showing 1-10 of 23 results. Next