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.

User: Thotsaporn Thanatipanonda

Thotsaporn Thanatipanonda's wiki page.

Thotsaporn Thanatipanonda has authored 4 sequences.

A207818 The sum of the second powers of the numbers of solid standard Young tableaux over all planar partitions of n.

Original entry on oeis.org

1, 3, 15, 105, 981, 11775, 174309, 3070293, 62728749, 1462046235, 38446605975, 1131448219263, 37011386961477, 1337106744965847, 53005310776229283, 2290750722850361415, 107258522028595441911, 5410293190992424617243, 292567014870308385871989
Offset: 1

Author

Keywords

Examples

			a(2) = 3 since the planar partitions [[2]], [[1,1]], [[1],[1]] in which each of these has only one tableaux.
		

References

  • Shalosh B. Ekhad and Doron Zeilberger, Computational and Theoretical Challenges On Counting Solid Standard Young Tableaux.

Programs

  • Maple
    # see link above for program.

A207816 Number of distinct necklaces with n red, n green, n blue and n white beads.

Original entry on oeis.org

1, 6, 318, 30804, 3941598, 586637256, 96197661156, 16875655269948, 3111284141045598, 595909785174057204, 117634021777132574568, 23797087019979071174580, 4912693780461352534397604, 1031629572413246016139181544, 219809927417367534490107035244, 47426945434432859336092700072304
Offset: 0

Author

Keywords

Examples

			For n=1, a(1)=6 since for four beads necklaces with each bead from each of the four colors say (R,G,B,W), we can arrange as following, [R,G,B,W], [R,G,W,B], [R,B,G,W], [R,B,W,G], [R,W,G,B] and [R,W,B,G].
		

Crossrefs

Column k=4 of A208183. - Alois P. Heinz, Feb 24 2012

Programs

  • Maple
    with(combinat): with(numtheory):
    # This formula comes from Polya Counting Theorem:
    # Z(C_n) = add(phi(d)*(a_d)^(n/d), d in divisors(n))/n;
    PolyaBrace:= proc(S) option remember; local n, s, d;
                   n:= add(s, s=S);
                   add(phi(d) *PolyaCoeff(d, S), d=divisors(n))/n
                 end:
    # Find coeff of prod(a[i]^s[i], i=1..n) of a_d^(n/d) (symmetric function)
    PolyaCoeff:= proc(d, S) option remember; local n, pow, s;
                   n:= add(s, s=S);
                   pow:= n/d;
                   if {seq(s mod d, s = S)} = {0}
                      then multinomial(pow, seq(s/d, s = S))
                      else 0
                   fi:
                 end:
    a:= n-> `if`(n=0, 1, PolyaBrace([n$4])):
    seq(a(n), n=0..20);
  • Mathematica
    a[n_] := DivisorSum[n, EulerPhi[n/#] (4#)!/(#!^4 * 4n)&]; a[0]=1;
    Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Mar 24 2017, after Alois P. Heinz *)

Formula

a(n) = Sum_{d|n} phi(n/d)*(4*d)!/(d!^4*4*n) if n>0 and a(0) = 1. - Alois P. Heinz, Feb 24 2012
a(n) ~ 2^(8*n-5/2) / (Pi^(3/2) * n^(5/2)). - Vaclav Kotesovec, Aug 23 2015

A207817 a(n) = (4*n)! / (n!^4 * (n+1)).

Original entry on oeis.org

1, 12, 840, 92400, 12612600, 1955457504, 329820499008, 59064793444800, 11062343605599000, 2145275226626532000, 427760079188506384320, 87255985739923260973440, 18139177035549431752363200, 3831766983249199488516960000, 820623729024838763928509760000
Offset: 0

Author

Keywords

Comments

Number of walks in 4-dimensions using steps (1,0,0,0), (0,1,0,0), (0,0,1,0) and (0,0,0,1) from (0,0,0,0) to (n,n,n,n) such that after each step we have y>=x.
Number of possible necklaces consisting of n white beads, n-1 red beads, n-1 green beads, and n-1 blue beads (two necklaces are considered equivalent if they differ by a cyclic permutation).
Note: the generalizations of this formula and the relation between d-dimensional walks and d-colored necklaces are also true for all d, d>=5.

Programs

  • Maple
    with(combinat, multinomial): seq(multinomial(4*n, n$4)/(n+1), n=0..20);
  • Mathematica
    CoefficientList[Series[HypergeometricPFQ[{1/4, 1/2, 3/4}, {1, 2}, 256 x], {x, 0, 20}], x] (* Benedict W. J. Irwin, Jul 13 2016 *)

Formula

G.f.: 3F2(1/4,1/2,3/4;1,2;256*x). - Benedict W. J. Irwin, Jul 13 2016
D-finite with recurrence n^2*(n+1)*a(n) -8*(4*n-3)*(2*n-1)*(4*n-1)*a(n-1)=0. - R. J. Mathar, Sep 27 2020

A175707 Number of ways to put n copies of 1,2,3,4 into sets.

Original entry on oeis.org

1, 15, 139, 862, 4079, 15791, 52450, 154279, 411180, 1009741, 2314278, 5000125, 10264997, 20152950, 38037517, 69323949, 122448455, 210271756, 351989816, 575711716, 921889652, 1447822620, 2233501928, 3389114724, 5064582169, 7461570579, 10848490675, 15579077786, 22115241763, 31054971635, 43166197978, 59427633555, 81077755892, 109673237289, 147158299390, 195946638641
Offset: 0

Author

Keywords

Comments

Related to generalized Bell Numbers.
The n copies of each digit must be in different sets, and the sets must be nonempty.
Other definition: Number of ways to distribute n copies of 1,2,3,4 into an arbitrary number of (nonempty) sets. Due to the nature of sets, the same digit may not be several times in the same set.

Examples

			For n=1, the solution is the fourth term of Bell numbers A000110.
For n=2, one way to partition 2 copies of 1, 2 copies of 2, 2 copies of 3 and 2 copies of 4 is {1}{2}{34}{12}{34}. On the other hand {112}{34}{23}{4} is not allowed since the same numbers are in the same set {112}.
		

Crossrefs

Programs

  • Maple
    a:= n-> (5382*n^11 +236808*n^10 +4643760*n^9 +53507520*n^8 +402098796*n^7 +2067612624*n^6 +7421736960*n^5 +18616942080*n^4 +32101468047*n^3 +36555545268*n^2 +25131098880*n +8024016000 +7016625*(-1)^n*n^3 +84199500*(-1)^n*n^2 +359251200*(-1)^n*n +538876800*(-1)^n) /(2^11*3^7*5^2*7*11) +5/3^6*(-1)^n * (sin(n*Pi/3)/sqrt(3)+ cos(n*Pi/3));
    seq(a(n), n=0..40);
    seq(SeqBrnDJ(n,4)[5], n=1..6); # using the Maple package BABUSHKAS (see links)
  • Mathematica
    LinearRecurrence[{7, -17, 8, 36, -60, 4, 56, -22, -22, -22, 56, 4, -60, 36, 8, -17, 7, -1}, {1, 15, 139, 862, 4079, 15791, 52450, 154279, 411180, 1009741, 2314278, 5000125, 10264997, 20152950, 38037517, 69323949, 122448455, 210271756}, 36] (* Jean-François Alcover, Nov 13 2018 *)

Formula

a(n) = (5382*n^11 +236808*n^10 +4643760*n^9 +53507520*n^8 +402098796*n^7 +2067612624*n^6 +7421736960*n^5 +18616942080*n^4 +32101468047*n^3 +36555545268*n^2 +25131098880*n +8024016000 +7016625*(-1)^n*n^3 +84199500*(-1)^n*n^2 +359251200*(-1)^n*n +538876800*(-1)^n) / (2^11*3^7*5^2*7*11) +5/3^6*(-1)^n * (sin(n*Pi/3)/sqrt(3) +cos(n*Pi/3)).
Recurrence: a(n) -7*a(n-1) +17*a(n-2) -8*a(n-3) -36*a(n-4) +60*a(n-5) -4*a(n-6) -56*a(n-7) +22*a(n-8) +22*a(n-9) +22*a(n-10) -56*a(n-11) -4*a(n-12) +60*a(n-13) -36*a(n-14) -8*a(n-15) +17*a(n-16) -7*a(n-17) +a(n-18) = 0.
G.f.: (x^10 +8*x^9 +51*x^8 +136*x^7 +252*x^6 +300*x^5 +252*x^4 +136*x^3 +51*x^2 +8*x+1) / ((x^2+x+1)*(x+1)^4*(x-1)^12).