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 1-4 of 4 results.

A001500 Number of stochastic matrices of integers: n X n arrays of nonnegative integers with all row and column sums equal to 3.

Original entry on oeis.org

1, 1, 4, 55, 2008, 153040, 20933840, 4662857360, 1579060246400, 772200774683520, 523853880779443200, 477360556805016931200, 569060910292172349004800, 868071731152923490921728000, 1663043727673392444887284377600, 3937477620391471128913917360384000
Offset: 0

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Author

Keywords

Comments

Also, number of bicubical multigraphs on 2n labeled nodes of two colors [Read, 1958, 1971]. - N. J. A. Sloane, Sep 09 2014

Examples

			a(2) = 4 with: [0 3]    [1 2]    [2 1]    [3 0]
               [3 0],   [2 1],   [1 2],   [0 3]. - _Bernard Schott_, Oct 15 2019
		

References

  • L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 125, Problem 25(4), b_n (but beware errors).
  • I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, John Wiley and Sons, N.Y., 1983.
  • R. C. Read, Some Enumeration Problems in Graph Theory. Ph.D. Dissertation, Department of Mathematics, Univ. London, 1958.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
  • M. L. Stein and P. R. Stein, Enumeration of Stochastic Matrices with Integer Elements. Report LA-4434, Los Alamos Scientific Laboratory of the University of California, Los Alamos, NM, Jun 1970.

Crossrefs

Row sums of A269743 and of A344379.
Column k=3 of A257493.

Programs

  • Mathematica
    a[n_] := 6^(-n) Sum[2^j 3^k n!^2 (3n - 2k - 3j)!/(j! k! (n - j - k)!^2 * 6^(n - j - k)), {j, 0, n}, {k, 0, n - j}];
    a /@ Range[0, 15] (* Jean-François Alcover, Oct 15 2019, after Shanzhen Gao *)

Formula

From Vladeta Jovovic, Mar 26 2001: (Start)
E.g.f. y(x) = Sum_{n >= 0} a(n)*x^n/(n!)^2 satisfies differential equation 81*x^5*(x^4 - x^2 + x + 4)*(d^4/dx^4)y(x) + 324*x^4*(x^4 - x^2 + x + 4)*(d^3/dx^3)y(x) - 9*x*(x^10 - 4*x^9 + 22*x^8 - 8*x^7 - 22*x^6 + 8*x^5 + 106*x^4 + 234*x^3 + 48*x^2 - 320*x + 64)*(d^2/dx^2)y(x) - 9*(x^10 - 4*x^9 + 22*x^8 - 8*x^7 - 4*x^6 + 8*x^5 + 88*x^4 + 252*x^3 + 120*x^2 - 320*x + 64)*(d/dx)y(x) + (x^11 - 7*x^10 + 30*x^9 - 16*x^8 - 43*x^7 + 51*x^6 + 238*x^5 + 630*x^4 + 36*x^3 - 1944*x^2 - 1152*x + 576)*y(x) = 0.
Recurrence: a(n) = n!*v(n) where v(n) = 1/(576*n)*((-198*n^9 + 8712*n^8 - 165175*n^7 + 1764196*n^6 - 11643772*n^5 + 48965728*n^4 - 130257475*n^3 + 209370724*n^2 - 182126340*n + 64083600)*v(n - 8) + (36*n^10 - 1944*n^9 + 45884*n^8 - 621504*n^7 + 5330892*n^6 - 30123576*n^5 + 112954596*n^4 - 275612976*n^3 + 415021552*n^2 - 343920960*n + 116928000)*v(n - 9) + (-9*n^11 + 585*n^10 - 16800*n^9 + 280800*n^8 - 3027357*n^7 + 22034565*n^6 - 110039130*n^5 + 375129450*n^4 - 849926784*n^3 + 1208298600*n^2 - 958439520*n + 315705600)*v(n - 10) + (-7*n^10 + 385*n^9 - 9240*n^8 + 127050*n^7 - 1104411*n^6 + 6314385*n^5 - 23918510*n^4 + 58866500*n^3 - 89275032*n^2 + 74400480*n - 25401600)*v(n - 11) + (-81*n^7 + 1944*n^6 - 20232*n^5 + 115578*n^4 - 383283*n^3 + 724230*n^2 - 708372*n + 270216)*v(n - 4) + (-72*n^6 + 1440*n^5 - 10890*n^4 + 40500*n^3 - 78678*n^2 + 75780*n - 28080)*v(n - 5) + (81*n^9 - 3321*n^8 + 59004*n^7 - 594054*n^6 + 3718687*n^5 - 14927199*n^4 + 38152096*n^3 - 59311746*n^2 + 50236612*n - 17330160)*v(n - 6) + (72*n^8 - 2520*n^7 + 37347*n^6 - 304479*n^5 + 1484133*n^4 - 4394565*n^3 + 7642248*n^2 - 7039116*n + 2576880)*v(n - 7) + (n^11 - 66*n^10 + 1925*n^9 - 32670*n^8 + 357423*n^7 - 2637558*n^6 + 13339535*n^5 - 45995730*n^4 + 105258076*n^3 - 150917976*n^2 + 120543840*n - 39916800)*v(n - 12) + (2880*n^2 - 5760*n + 3456)*v(n - 1) + (324*n^5 - 3564*n^4 + 14148*n^3 - 26028*n^2 + 21312*n - 6192)*v(n - 2) + (81*n^6 - 1377*n^5 + 7209*n^4 - 13203*n^3 - 3402*n^2 + 32076*n - 21384)*v(n - 3)). (End)
a(n) = 6^(-n) * Sum_{ alpha = 0..n, beta = 0..n-alpha } (2^alpha*3^beta*(n!)^2*(-2*beta+3*n-3*alpha)!)/(alpha!*beta!*(n-alpha-beta)!^2*6^(n-alpha-beta)). - Shanzhen Gao, Nov 05 2007
a(n) ~ sqrt(Pi) * 3^(n + 1/2) * n^(3*n + 1/2) / (2^(2*n - 1/2) * exp(3*n - 2)). - Vaclav Kotesovec, Oct 15 2019

Extensions

More terms from Vladeta Jovovic, Mar 26 2001

A260583 Number of ways to place 3n rooks on an n X n board, 3 rooks in each row and each column, multiple rooks in an allowed cell, and exactly 4 rooks below the main diagonal.

Original entry on oeis.org

11, 595, 14679, 253247, 3564803, 44226950, 505572550, 5473391465, 57122380066, 581477852342, 5819301681925, 57564437594318, 564911137682637, 5513703983635512, 53616132982114742, 520057429817203110, 5035740328012627416, 48704838658567681135
Offset: 3

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Author

Esther Banaian, Jul 29 2015

Keywords

Comments

a(n) is the number of minimal multiplex juggling patterns of period n using exactly 4 balls when we can catch/throw up to 3 balls at a time. (Minimal in the sense that the throw heights are between 0 and n-1.)

Crossrefs

Column k=4 of A269743.

Formula

G.f.: -(24558000*x^24 - 221169800*x^23 + 1030045255*x^22 - 3270869391*x^21 + 7705144467*x^20 - 13843184523*x^19 + 19209151138*x^18 - 20800159606*x^17 + 17768204859*x^16 - 12126221923*x^15 + 6718636422*x^14 - 3086566305*x^13 + 1204914514*x^12 - 407103232*x^11 + 118646908*x^10 - 28836372*x^9 + 5505383*x^8 - 758705*x^7 + 65305*x^6 - 2162*x^5 - 131*x^4 + 11*x^3)/(133600000*x^25 - 1875920000*x^24 + 12500686000*x^23 - 52604444000*x^22 + 156920670600*x^21 - 353103818000*x^20 + 622718972395*x^19 - 882777307660*x^18 + 1023713051333*x^17 - 983132187597*x^16 + 788634518440*x^15 - 531447118763*x^14 + 301890662895*x^13 - 144761728498*x^12 + 58568440406*x^11 - 19945788669*x^10 + 5692551701*x^9 - 1352405718*x^8 + 264899104*x^7 - 42210805*x^6 + 5370925*x^5 - 531418*x^4 + 39303*x^3 - 2039*x^2 + 66*x - 1).

A260727 Number of ways to place 3n rooks on an n X n board, with 3 rooks in each row and each column, multiple rooks in a cell allowed, and exactly 3 rooks below the main diagonal.

Original entry on oeis.org

1, 23, 325, 3368, 28819, 218788, 1539399, 10314315, 66953292, 425761614, 2671506918, 16618186770, 102796975770, 633596982417, 3896224129259, 23924104985984, 146764696175937, 899809941054468, 5514653407814317, 33789681789605283, 207007665004469906
Offset: 2

Views

Author

Chris Cox, Jul 30 2015

Keywords

Comments

a(n) is the number of minimal multiplex juggling patterns of period n using exactly 3 balls when we can catch/throw up to 3 balls at a time. (Minimal in the sense that each of the n throws is between 0 and n-1, inclusive.)

Crossrefs

Column k=3 of A269743.

Programs

  • Mathematica
    CoefficientList[Series[-(700*x^13 - 2435*x^12 + 4558*x^11 - 7532*x^10 + 10404*x^9 - 9697*x^8 + 5545*x^7 - 1844*x^6 + 336*x^5 - 39*x^4 + 7*x^3 - x^2)/((x^2)*(4000*x^14 - 35400*x^13 + 143100*x^12 - 349910*x^11 + 577675*x^10 - 680496*x^9 + 589248*x^8 - 380592*x^7 + 184037*x^6 - 66214*x^5 + 17423*x^4 - 3246*x^3 + 404*x^2 - 30*x + 1)), {x, 0, 20}], x] (* Wesley Ivan Hurt, Jul 30 2015 *)

Formula

G.f.: -(700*x^13 - 2435*x^12 + 4558*x^11 - 7532*x^10 + 10404*x^9 - 9697*x^8 + 5545*x^7 - 1844*x^6 + 336*x^5 - 39*x^4 + 7*x^3 - x^2)/(4000*x^14 - 35400*x^13 + 143100*x^12 - 349910*x^11 + 577675*x^10 - 680496*x^9 + 589248*x^8 - 380592*x^7 + 184037*x^6 - 66214*x^5 + 17423*x^4 - 3246*x^3 + 404*x^2 - 30*x + 1).

A269742 Triangle of generalized Eulerian numbers T(n,k) = _2 read by rows, n >= 1, 0 <= k < 2*n.

Original entry on oeis.org

1, 1, 1, 1, 1, 4, 11, 4, 1, 1, 11, 72, 114, 72, 11, 1, 1, 26, 367, 1492, 2438, 1492, 367, 26, 1, 1, 57, 1630, 13992, 48965, 73120, 48965, 13992, 1630, 57, 1, 1, 120, 6680, 109538, 727982, 2169674, 3107640, 2169674, 727982, 109538, 6680, 120, 1
Offset: 1

Views

Author

N. J. A. Sloane, Mar 16 2016

Keywords

Comments

T(n,k) is the number of nonnegative integer n X n matrices with every row and column sum 2 and sum of entries below the main diagonal k. The case when every row and column sum is 1 is given by the Eulerian numbers (A008292). - Andrew Howroyd, Feb 22 2020

Examples

			Triangle begins:
  1;
  1, 1, 1;
  1, 4, 11, 4, 1;
  1, 11, 72, 114, 72, 11, 1;
  1, 26, 367, 1492, 2438, 1492, 367, 26, 1;
  1, 57, 1630, 13992, 48965, 73120, 48965, 13992, 1630, 57, 1;
  ...
The matrices for row n=3, k=0..2 are:
  [2 0]  [1 1]  [0 2]
  [0 2]  [1 1]  [2 0]
		

Crossrefs

Row sums are A000681.
Columns k=0..4 are A000012, A000295, A260585, A260575, A260582.
Central coefficients are A332729.

Programs

Extensions

Terms a(26) and beyond from Andrew Howroyd, Feb 22 2020
Showing 1-4 of 4 results.