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.

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A308292 A(n,k) = Sum_{i_1=0..n} Sum_{i_2=0..n} ... Sum_{i_k=0..n} multinomial(i_1 + i_2 + ... + i_k; i_1, i_2, ..., i_k), square array A(n,k) read by antidiagonals, for n >= 0, k >= 0.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 5, 3, 1, 1, 16, 19, 4, 1, 1, 65, 271, 69, 5, 1, 1, 326, 7365, 5248, 251, 6, 1, 1, 1957, 326011, 1107697, 110251, 923, 7, 1, 1, 13700, 21295783, 492911196, 191448941, 2435200, 3431, 8, 1, 1, 109601, 1924223799, 396643610629, 904434761801, 35899051101, 55621567, 12869, 9, 1
Offset: 0

Views

Author

Seiichi Manyama, May 19 2019

Keywords

Comments

For r > 1, row r is asymptotic to sqrt(2*Pi) * (r*n)^(r*n + 1/2) / ((r!)^n * exp(r*n-1)). - Vaclav Kotesovec, May 24 2020

Examples

			For (n,k) = (3,2), (Sum_{i=0..3} x^i/i!)^2 = (1 + x + x^2/2 + x^3/6)^2 = 1 + 2*x + 4*x^2/2 + 8*x^3/6 + 14*x^4/24 + 20*x^5/120 + 20*x^6/720. So A(3,2) = 1 + 2 + 4 + 8 + 14 + 20 + 20 = 69.
Square array begins:
   1, 1,    1,        1,             1,                   1, ...
   1, 2,    5,       16,            65,                 326, ...
   1, 3,   19,      271,          7365,              326011, ...
   1, 4,   69,     5248,       1107697,           492911196, ...
   1, 5,  251,   110251,     191448941,        904434761801, ...
   1, 6,  923,  2435200,   35899051101,    1856296498826906, ...
   1, 7, 3431, 55621567, 7101534312685, 4098746255797339511, ...
		

Crossrefs

Columns k=0..4 give A000012, A000027(n+1), A030662(n+1), A144660, A144661.
Rows n=0..4 give A000012, A000522, A003011, A308294, A308295.
Main diagonal gives A274762.
Cf. A144510.

Formula

A(n,k) = Sum_{i=0..k*n} b(i) where Sum_{i=0..k*n} b(i) * x^i/i! = (Sum_{i=0..n} x^i/i!)^k.

A144661 a(n) = Sum_{i=0..n} Sum_{j=0..n} Sum_{k=0..n} Sum_{l=0..n} (i+j+k+l)!/(i!*j!*k!*l!).

Original entry on oeis.org

1, 65, 7365, 1107697, 191448941, 35899051101, 7101534312685, 1458965717496881, 308290573348183629, 66577182435768923245, 14629025943480502591445, 3260160391173522631759533, 735119604833362632050789701, 167408468505328518543519208949, 38448088693846486556578015883325
Offset: 0

Views

Author

N. J. A. Sloane, Feb 01 2009

Keywords

Crossrefs

Programs

  • Maple
    f:=n->add( add( add( add( (i+j+k+l)!/(i!*j!*k!*l!), i=0..n),j=0..n),k=0..n),l=0..n); [seq(f(n),n=0..20)];
  • Mathematica
    Table[Sum[(i + j + k + l)! / (i!*j!*k!*l!), {i, 0, n}, {j, 0, n}, {k, 0, n}, {l, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Apr 02 2019 *)
    Table[Sum[(1 + j + k + l + n)!/((1 + j + k + l)*j!*k!*l!), {j, 0, n}, {k, 0, n}, {l, 0, n}] / n!, {n, 0, 20}] (* Vaclav Kotesovec, Apr 03 2019 *)
    Table[Sum[(1 + k + l + 2*n)! * HypergeometricPFQ[{1, -1 - k - l - n, -n}, {-1 - k - l - 2*n, -k - l - n}, 1] / ((1 + k + l + n)*k!*l!*n!), {k, 0, n}, {l, 0, n}]/n!, {n, 0, 20}] (* Vaclav Kotesovec, Apr 03 2019 *)
  • PARI
    {a(n) = sum(i=0, n, sum(j=0, n, sum(k=0, n, sum(l=0, n, (i+j+k+l)!/(i!*j!*k!*l!)))))} \\ Seiichi Manyama, Apr 02 2019

Formula

a(n) ~ 2^(8*n + 15/2) / (81 * Pi^(3/2) * n^(3/2)). - Vaclav Kotesovec, Apr 02 2019

A181991 n-alternating permutations of length 4n.

Original entry on oeis.org

1, 1385, 315523, 60376809, 11593285251, 2301250545971, 472105349529479, 99537885358650089, 21451428576293883859, 4705284467293276073635, 1047067375984978044542143, 235809039854522043890582835, 53644722291938408687646120103, 12309355014854205055828909176039
Offset: 1

Views

Author

Peter Luschny, Apr 05 2012

Keywords

Comments

a(n) = A181985(n,4).

Crossrefs

Programs

  • Maple
    A181991 := proc(n) local E, dim, i, k; dim := 4*n;
    E := array(0..dim, 0..dim); E[0, 0] := 1;
    for i from 1 to dim do
    if i mod n = 0 then E[i, 0] := 0 ;
       for k from i-1 by -1 to 0 do E[k, i-k] := E[k+1, i-k-1] + E[k, i-k-1] od;
    else E[0, i] := 0;
       for k from 1 by 1 to i do E[k, i-k] := E[k-1, i-k+1] + E[k-1, i-k] od;
    fi od; E[0, dim] end:
    seq(A181991(n), n = 1..14);
    # Alternatively:
    a := (x) -> (4*x)!*(-1/(4*x)!+2/x!/(3*x)!+1/(2*x)!^2-3/x!^2/(2*x)!+1/x!^4):
    seq(a(n), n=1..14); # Peter Luschny, Aug 13 2015
  • Mathematica
    A181985[n_, len_] := Module[{e, dim = n*(len - 1)}, e[0, 0] = 1; For[i = 1, i <= dim, i++, If[Mod[i, n] == 0, e[i, 0] = 0; For[k = i - 1, k >= 0, k--, e[k, i - k] = e[k + 1, i - k - 1] + e[k, i - k - 1]], e[0, i] = 0; For[k = 1, k <= i, k++, e[k, i - k] = e[k - 1, i - k + 1] + e[k - 1, i - k]]]]; Table[e[0, n*k], {k, 0, len - 1}]]; a[n_] := A181985[n, 4 + 1][[4 + 1]]; Table[a[n], {n, 1, 14}] (* Jean-François Alcover, Dec 17 2013, after Maple code in A181985 *)

Formula

a(n) = (4*n)!*(-1/(4*n)! + 2/(n!*(3*n)!) + 1/(2*n)!^2 - 3/(n!^2*(2*n)!) + 1/n!^4). - Peter Luschny, Aug 13 2015

A206735 Triangle T(n,k), read by rows, given by (0, 2, -1/2, 1/2, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (1, 0, -1/2, 1/2, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 0, 1, 0, 2, 1, 0, 3, 3, 1, 0, 4, 6, 4, 1, 0, 5, 10, 10, 5, 1, 0, 6, 15, 20, 15, 6, 1, 0, 7, 21, 35, 35, 21, 7, 1, 0, 8, 28, 56, 70, 56, 28, 8, 1, 0, 9, 36, 84, 126, 126, 84, 36, 9, 1, 0, 10, 45, 120, 210, 252, 210, 120, 45, 10, 1, 0, 11, 55, 165, 330, 462, 462, 330, 165, 55, 11, 1
Offset: 0

Views

Author

Philippe Deléham, Feb 11 2012

Keywords

Comments

A103452*A007318 as infinite lower triangular matrices.
Essentially the same as A199011.

Examples

			Triangle begins :
1
0, 1
0, 2, 1
0, 3, 3, 1
0, 4, 6, 4, 1
0, 5, 10, 10, 5, 1
0, 6, 15, 20, 15, 6, 1
0, 7, 21, 35, 35, 21, 7, 1
0, 8, 28, 56, 70, 56, 28, 8, 1
0, 9, 36, 84, 126, 126, 84, 36, 9, 1
0, 10, 45, 120, 210, 252, 210, 120, 45, 10, 1
0, 11, 55, 165, 330, 462, 462, 330, 165, 55, 11, 1
		

Crossrefs

Cf. A007318, A000071 (antidiagonal sums).

Formula

T(n,k) = A007318(n,k) - A073424(n,k).
Sum_{k, 0<=k<=n} T(n,k)*x^k = (1+x)^n - 1 + 0^n.
T(n,0) = 0^n = A000007(n), T(n,k) = binomial(n,k) for k>0.
G.f.: (1-2*x+(1+y)*x^2)/(1-2x+(1+y)*x^2-y*x).
Sum{k, 0<=k<=n} T(n,k)^x = A000027(n+1), A000225(n), A030662(n), A096191(n), A096192(n) for x = 0, 1, 2, 3, 4 respectively.

A211213 n-alternating permutations of length 3n.

Original entry on oeis.org

1, 61, 1513, 33661, 750751, 17116009, 398840401, 9464040829, 227864057851, 5550936701311, 136526608389601, 3384729259165801, 84478081828015513, 2120572560190269841, 53494979095639780513, 1355345459896317255037, 34469858667289041256051, 879619727291950363099291
Offset: 1

Views

Author

Peter Luschny, Apr 05 2012

Keywords

Comments

a(n) = A181985(n,3).

Crossrefs

Programs

  • Maple
    A211213 := proc(n) local E, dim, i, k; dim := 3*n;
    E := array(0..dim, 0..dim); E[0, 0] := 1;
    for i from 1 to dim do
    if i mod n = 0 then E[i, 0] := 0 ;
       for k from i-1 by -1 to 0 do E[k, i-k] := E[k+1, i-k-1] + E[k, i-k-1] od;
    else E[0, i] := 0;
       for k from 1 by 1 to i do E[k, i-k] := E[k-1, i-k+1] + E[k-1, i-k] od;
    fi od; E[0, dim] end:
    seq(A211213(n), n = 1..18);
    # Alternatively:
    a := x -> (3*x)!*(1/(3*x)!-2/(x!*(2*x)!)+1/(x!)^3):
    seq(a(n),n=1..18); # Peter Luschny, Aug 13 2015
  • Mathematica
    nmax = 18; a[n_] := Module[{e, dim = n*(nmax-1)}, e[0, 0] = 1; For[i = 1, i <= dim, i++, If[Mod[i, n] == 0 , e[i, 0] = 0; For[k = i-1, k >= 0, k--, e[k, i-k] = e[k+1, i-k-1] + e[k, i-k-1] ], e[0, i] = 0; For[k = 1, k <= i, k++, e[k, i-k] = e[k-1, i-k+1] + e[k-1, i-k] ] ]]; e[0, 3*n]] ; Table[a[n], {n, 1, nmax}] (* Jean-François Alcover, Jul 26 2013, after Maple *)

Formula

a(n) = (3*n)!*(1/(3*n)!-2/(n!*(2*n)!)+1/(n!)^3). - Peter Luschny, Aug 13 2015

A322938 a(n) = binomial(2*n + 2, n + 2) - 1.

Original entry on oeis.org

0, 3, 14, 55, 209, 791, 3002, 11439, 43757, 167959, 646645, 2496143, 9657699, 37442159, 145422674, 565722719, 2203961429, 8597496599, 33578000609, 131282408399, 513791607419, 2012616400079, 7890371113949, 30957699535775, 121548660036299, 477551179875951
Offset: 0

Views

Author

Peter Luschny, Feb 13 2019

Keywords

Crossrefs

Cf. A001791, A014473, A030662 (d=0), A010763 (d=1), this sequence (d=2).

Programs

  • Magma
    [Binomial(2*n+2,n+2) -1: n in [0..30]]; // G. C. Greubel, Apr 22 2024
    
  • Maple
    aList := proc(len) local gf, ser; assume(Im(x) > 0);
    gf := (2*x^2 - x + 1)/(2*(x - 1)*x^2) - (I*(2*x - 1))/(2*x^2*sqrt(4*x - 1));
    ser := series(gf, x, len+4):
    seq(coeff(ser, x, n), n=0..len) end: lprint(aList(25));
  • Mathematica
    Table[Binomial[2 n + 2, n + 2] - 1, {n, 0, 25}]
  • SageMath
    [binomial(2*n+2,n+2) - 1 for n in range(31)] # G. C. Greubel, Apr 22 2024

Formula

Let G(x) = (2*x^2-x+1)/(2*(x-1)*x^2)-(I*(2*x-1))/(2*x^2*sqrt(4*x-1)) with Im(x) > 0, then a(n) = [x^n] G(x). The generating function G(x) satisfies the differential equation 9*x - 16*x^2 + 4*x^3 = (8*x^5 - 22*x^4 + 21*x^3 - 8*x^2 + x)*diff(G(x), x) + (12*x^4 - 36*x^3 + 38*x^2 - 16*x + 2)*G(x).
From Peter Bala, Feb 25 2022: (Start)
a(n) = Sum_{k = 0..n+1} binomial(n+k,k+1).
a(n) = Sum_{k = 0..n-1} binomial(n+k+2,k+1).
More generally, Sum_{k = 0..n+m} binomial(n+k,k+1) = Sum_{k = 0..n-1} binomial(n+k+m+1,k+1) = binomial(2*n+m+1,n) - 1. (End)
a(n) = A001791(n+1) - 1. - Hugo Pfoertner, Feb 26 2022
a(n) = n/(n+2) * binomial(2*n+2, n+1) * Sum_{k = 0..n+1} 1/binomial(n+k+1, k). - Peter Bala, Aug 05 2025

A165257 Triangle in which n-th row is binomial(n+k-1,k), for column k=1..n.

Original entry on oeis.org

1, 2, 3, 3, 6, 10, 4, 10, 20, 35, 5, 15, 35, 70, 126, 6, 21, 56, 126, 252, 462, 7, 28, 84, 210, 462, 924, 1716, 8, 36, 120, 330, 792, 1716, 3432, 6435, 9, 45, 165, 495, 1287, 3003, 6435, 12870, 24310
Offset: 1

Views

Author

Daniel McLaury (daniel.mclaury(AT)gmail.com), Sep 11 2009

Keywords

Comments

T(n,k) is the number of non-descending sequences with length k and last number is less or equal to n. T(n,k) is also the number of integer partitions (of any positive integer) with length k and largest part is less or equal to n. - Zlatko Damijanic, Dec 06 2024

Examples

			1;
2, 3;
3, 6, 10;
4, 10, 20, 35;
5, 15, 35, 70, 126;
6, 21, 56, 126, 252, 462;
7, 28, 84, 210, 462, 924, 1716;
		

Crossrefs

A059481 with the first column (k = 0) removed.
Cf. A030662 (row sums), A001700 (diagonal).

Programs

  • Mathematica
    Table[Binomial[n+k-1,k],{n,10},{k,n}]//Flatten (* Harvey P. Dale, Jul 31 2021 *)
  • PARI
    tabl(nn) = {for (n=1, nn, for (k=1, n, print1( binomial(n+k-1, k), ", ");); print(););} \\ Michel Marcus, Jun 12 2013

A331673 Sum of all base-n numbers with digit sum n and length exactly n.

Original entry on oeis.org

3, 79, 2299, 84361, 3872406, 216591677, 14378073683, 1107635176621, 97229999995138, 9583904327477305, 1048274845801847390, 126003010469828661807, 16510208629407273871884, 2342241434486480710216185, 357676630651821282153992579, 58498575553741083746904253333
Offset: 2

Views

Author

Alois P. Heinz, Feb 22 2020

Keywords

Comments

The cardinality of these numbers is given by A030662(n-1)

Examples

			a(2) = 3 = 11_2.
a(3) = 79 = 11 + 13 + 15 + 19 + 21 = 102_3 + 111_3 + 120_3 + 201_3 + 210_3.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, [1, 0],
          `if`(i=0, 0, add((p->[p[1], p[2]*k+p[1]*d])(
             b(n-d, i-1, k)), d=0..min(n, k-1))))
        end:
    a:= n-> b(n$3)[2]-b(n, n-1, n)[2]:
    seq(a(n), n=2..17);

A375694 Number A(n,k) of multiset permutations of {{1}^k, {2}^k, ..., {n}^k} with no fixed k-tuple {j}^k; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 5, 2, 0, 1, 0, 19, 74, 9, 0, 1, 0, 69, 1622, 2193, 44, 0, 1, 0, 251, 34442, 362997, 101644, 265, 0, 1, 0, 923, 756002, 62924817, 166336604, 6840085, 1854, 0, 1, 0, 3431, 17150366, 11729719509, 305225265804, 136221590695, 630985830, 14833, 0
Offset: 0

Views

Author

Alois P. Heinz, Aug 24 2024

Keywords

Examples

			A(2,2) = 5: 1212, 1221, 2112, 2121, 2211.
A(2,3) = 19: 112122, 112212, 112221, 121122, 121212, 121221, 122112, 122121, 122211, 211122, 211212, 211221, 212112, 212121, 212211, 221112, 221121, 221211, 222111.
A(3,2) = 74: 121323, 121332, 122313, 122331, 123123, 123132, 123213, 123231, 123312, 123321, 131223, 131232, 131322, 132123, 132132, 132312, 132321, 133122, 133212, 133221, 211323, 211332, 212313, 212331, 213123, 213132, 213213, 213231, 213312, 213321, 221313, 221331, 223113, 223131, 223311, 231123, 231132, 231213, 231231, 231312, 231321, 232113, 232131, 232311, 233112, 233121, 233211, 311223, 311232, 311322, 312123, 312132, 312312, 312321, 313122, 313212, 313221, 321123, 321132, 321213, 321231, 321312, 321321, 322113, 322131, 322311, 323112, 323121, 323211, 331122, 331212, 331221, 332112, 332121.
A(4,1) = 9: 2143, 2341, 2413, 3142, 3412, 3421, 4123, 4312, 4321.
Square array A(n,k) begins:
  1,  1,      1,         1,            1,               1, ...
  0,  0,      0,         0,            0,               0, ...
  0,  1,      5,        19,           69,             251, ...
  0,  2,     74,      1622,        34442,          756002, ...
  0,  9,   2193,    362997,     62924817,     11729719509, ...
  0, 44, 101644, 166336604, 305225265804, 623302086965044, ...
		

Crossrefs

Columns k=0-2 give: A000007, A000166, A374980.
Rows n=0-2 give: A000012, A000004, A030662.
Main diagonal gives A375693.

Programs

  • Maple
    A:= (n, k)-> add((-1)^(n-j)*binomial(n, j)*(k*j)!/k!^j, j=0..n):
    seq(seq(A(n, d-n), n=0..d), d=0..10);

Formula

A(n,k) = Sum_{j=0..n} (-1)^(n-j)*binomial(n,j)*(k*j)!/k!^j.

A237664 Interpolation polynomial through n+1 points (0,1), (1,1), ..., (n-1,1) and (n,n) evaluated at 2n.

Original entry on oeis.org

0, 1, 7, 41, 211, 1009, 4621, 20593, 90091, 388961, 1662805, 7054321, 29745717, 124807201, 521515801, 2171645281, 9016205851, 37337699521, 154277300101, 636214748401, 2619084047581, 10765157488801, 44186078238121, 181135476007201, 741694884711301
Offset: 0

Views

Author

Alois P. Heinz, Feb 11 2014

Keywords

Crossrefs

Cf. A000290 (evaluated at n+1), A127736 (at n+2), A237622 (n points).

Programs

  • Maple
    a:= proc(n) option remember; `if`(n<2, n,
           ((n-1)*(3*n-4)*(5*n-3) *a(n-1)
            -2*(2*n-3)*(3*n^2-4*n+2) *a(n-2))/
            (n*(3*n^2-10*n+9)))
        end:
    seq(a(n), n=0..30);
  • Mathematica
    CoefficientList[Series[(6*x-1)/Sqrt[1-4*x]^3-1/(x-1), {x, 0, 20}], x] (* Vaclav Kotesovec, Feb 14 2014 *)
    a[n_] := Module[{m}, InterpolatingPolynomial[Table[{k, If[k == n, n, 1]}, {k, 0, n}], m] /. m -> 2n];
    a /@ Range[0, 30] (* Jean-François Alcover, Dec 22 2020 *)

Formula

G.f.: (6*x-1)/sqrt(1-4*x)^3 - 1/(x-1).
a(n) ~ sqrt(n)*4^n/sqrt(Pi). - Vaclav Kotesovec, Feb 14 2014
From Gregory Morse, Mar 19 2021: (Start)
a(n) = (2*n)!*(n-1)/(n!)^2 + 1.
a(n) = A030662(n-1)*(n-1) + n, for n > 0. (End)
E.g.f.: exp(x) * (1 - exp(x) * ((1 - 2*x) * BesselI(0,2*x) - 2 * x * BesselI(1,2*x))). - Ilya Gutkovskiy, Nov 19 2021
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