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 1-8 of 8 results.

A327870 Row sums of A327869.

Original entry on oeis.org

1, 2, 2, 11, 14, 47, 305, 611, 2070, 8831, 84077, 204371, 944333, 3850407, 23991739, 297448526, 927586630, 4775902567, 24534836837, 141681919871, 1080484165089, 18553632475991, 66762080435239, 415657332495526, 2298883231736949, 15799818116227747
Offset: 0

Views

Author

Alois P. Heinz, Sep 28 2019

Keywords

Crossrefs

Row sums of A327869.
Cf. A320566.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(i*(i+1)/2 b(n$2, 0)*(n+1) -add(b(n$2, k), k=1..n):
    seq(a(n), n=0..28);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[i*(i + 1)/2 < n, 0,
         If[n == 0, 1, If[i < 2, 0, b[n, i - 1, If[i == k, 0, k]]] +
         If[i == k, 0, b[n - i, Min[n - i, i - 1], k]*Binomial[n, i]]]];
    a[n_] := b[n, n, 0]*(n + 1) - Sum[b[n, n, k], {k, 1, n}];
    Table[a[n], {n, 0, 28}] (* Jean-François Alcover, Mar 28 2022, after Alois P. Heinz *)

A007837 Number of partitions of n-set with distinct block sizes.

Original entry on oeis.org

1, 1, 1, 4, 5, 16, 82, 169, 541, 2272, 17966, 44419, 201830, 802751, 4897453, 52275409, 166257661, 840363296, 4321172134, 24358246735, 183351656650, 2762567051857, 10112898715063, 62269802986835, 343651382271526, 2352104168848091, 15649414071734847
Offset: 0

Views

Author

Keywords

Comments

Conjecture: the Gauss congruences a(n*p^k) == a(n*p^(k-1)) (mod p^k) hold for all primes p and positive integers n and k. Cf. A185895. - Peter Bala, Mar 17 2022

Examples

			From _Gus Wiseman_, Jul 13 2019: (Start)
The a(1) = 1 through a(5) = 16 set partitions with distinct block sizes:
  {{1}}  {{1,2}}  {{1,2,3}}    {{1,2,3,4}}    {{1,2,3,4,5}}
                  {{1},{2,3}}  {{1},{2,3,4}}  {{1},{2,3,4,5}}
                  {{1,2},{3}}  {{1,2,3},{4}}  {{1,2},{3,4,5}}
                  {{1,3},{2}}  {{1,2,4},{3}}  {{1,2,3},{4,5}}
                               {{1,3,4},{2}}  {{1,2,3,4},{5}}
                                              {{1,2,3,5},{4}}
                                              {{1,2,4},{3,5}}
                                              {{1,2,4,5},{3}}
                                              {{1,2,5},{3,4}}
                                              {{1,3},{2,4,5}}
                                              {{1,3,4},{2,5}}
                                              {{1,3,4,5},{2}}
                                              {{1,3,5},{2,4}}
                                              {{1,4},{2,3,5}}
                                              {{1,4,5},{2,3}}
                                              {{1,5},{2,3,4}}
(End)
		

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; `if`(n=0, 1, add(add((-d)*(-d!)^(-k/d),
           d=numtheory[divisors](k))*(n-1)!/(n-k)!*a(n-k), k=1..n))
        end:
    seq(a(n), n=0..30);  # Alois P. Heinz, Sep 06 2008
    # second Maple program:
    A007837 := proc(n) option remember; local k; `if`(n = 0, 1,
    add(binomial(n-1, k-1) * A182927(k) * A007837(n-k), k = 1..n)) end:
    seq(A007837(i),i=0..24); # Peter Luschny, Apr 25 2011
  • Mathematica
    nn=20;p=Product[1+x^i/i!,{i,1,nn}];Drop[Range[0,nn]!CoefficientList[ Series[p,{x,0,nn}],x],1]  (* Geoffrey Critzer, Sep 22 2012 *)
    a[0]=1; a[n_] := a[n] = Sum[(n-1)!/(n-k)!*DivisorSum[k, -#*(-#!)^(-k/#)&]* a[n-k], {k, 1, n}]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Nov 23 2015, after Vladeta Jovovic *)
  • PARI
    {my(n=20); Vec(serlaplace(prod(k=1, n, (1+x^k/k!) + O(x*x^n))))} \\ Andrew Howroyd, Dec 21 2017

Formula

E.g.f.: Product_{m >= 1} (1+x^m/m!).
a(n) = Sum_{k=1..n} (n-1)!/(n-k)!*b(k)*a(n-k), where b(k) = Sum_{d divides k} (-d)*(-d!)^(-k/d) and a(0) = 1. - Vladeta Jovovic, Oct 13 2002
E.g.f.: exp(Sum_{k>=1} Sum_{j>=1} (-1)^(k+1)*x^(j*k)/(k*(j!)^k)). - Ilya Gutkovskiy, Jun 18 2018

Extensions

More terms from Christian G. Bower
a(0)=1 prepended by Alois P. Heinz, Aug 29 2015

A327801 Sum T(n,k) of multinomials M(n; lambda), where lambda ranges over all partitions of n into parts incorporating k; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 1, 1, 3, 2, 1, 10, 9, 3, 1, 47, 40, 18, 4, 1, 246, 235, 100, 30, 5, 1, 1602, 1476, 705, 200, 45, 6, 1, 11481, 11214, 5166, 1645, 350, 63, 7, 1, 95503, 91848, 44856, 13776, 3290, 560, 84, 8, 1, 871030, 859527, 413316, 134568, 30996, 5922, 840, 108, 9, 1
Offset: 0

Views

Author

Alois P. Heinz, Sep 25 2019

Keywords

Comments

Here we assume that every list of parts has at least one 0 because its addition does not change the value of the multinomial.

Examples

			Triangle T(n,k) begins:
      1;
      1,     1;
      3,     2,     1;
     10,     9,     3,     1;
     47,    40,    18,     4,    1;
    246,   235,   100,    30,    5,   1;
   1602,  1476,   705,   200,   45,   6,  1;
  11481, 11214,  5166,  1645,  350,  63,  7, 1;
  95503, 91848, 44856, 13776, 3290, 560, 84, 8, 1;
  ...
		

Crossrefs

Columns k=0-2 give: A005651, A327827, A327828.
Row sums give A320566.
T(2n,n) gives A266518.
T(n,n-1) gives A001477.
T(n+1,n-1) gives A045943.
Cf. A327869.

Programs

  • Maple
    with(combinat):
    T:= (n, k)-> add(multinomial(add(i, i=l), l[], 0), l=
                 select(x-> k=0 or k in x, partition(n))):
    seq(seq(T(n, k), k=0..n), n=0..10);
    # second Maple program:
    b:= proc(n, i, k) option remember; `if`(n=0, 1,
          `if`(i<2, 0, b(n, i-1, `if`(i=k, 0, k)))+
          `if`(i=k, 0, b(n-i, min(n-i, i), k)/i!))
        end:
    T:= (n, k)-> n!*(b(n$2, 0)-`if`(k=0, 0, b(n$2, k))):
    seq(seq(T(n, k), k=0..n), n=0..10);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0, 1, If[i < 2, 0, b[n, i - 1, If[i == k, 0, k]]] + If[i == k, 0, b[n - i, Min[n - i, i], k]/i!]];
    T[n_, k_] := n! (b[n, n, 0] - If[k == 0, 0, b[n, n, k]]);
    Table[T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Apr 30 2020, from 2nd Maple program *)

A327884 Number T(n,k) of set partitions of [n] such that at least one of the block sizes is k or k=0; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 5, 4, 3, 1, 15, 11, 9, 4, 1, 52, 41, 35, 20, 5, 1, 203, 162, 150, 90, 30, 6, 1, 877, 715, 672, 455, 175, 42, 7, 1, 4140, 3425, 3269, 2352, 1015, 280, 56, 8, 1, 21147, 17722, 17271, 13132, 6237, 1890, 420, 72, 9, 1, 115975, 98253, 97155, 76540, 39480, 12978, 3150, 600, 90, 10, 1
Offset: 0

Views

Author

Alois P. Heinz, Sep 28 2019

Keywords

Examples

			T(4,1) = 11: 123|4, 124|3, 12|3|4, 134|2, 13|2|4, 1|234, 1|23|4, 14|2|3, 1|24|3, 1|2|34, 1|2|3|4.
T(4,2) = 9: 12|34, 12|3|4, 13|24, 13|2|4, 14|23, 1|23|4, 14|2|3, 1|24|3, 1|2|34.
T(4,3) = 4: 123|4, 124|3, 134|2, 1|234.
T(4,4) = 1: 1234.
T(5,1) = 41: 1234|5, 1235|4, 123|4|5, 1245|3, 124|3|5, 12|34|5, 125|3|4, 12|35|4, 12|3|45, 12|3|4|5, 1345|2, 134|2|5, 13|24|5, 135|2|4, 13|25|4, 13|2|45, 13|2|4|5, 14|23|5, 1|2345, 1|234|5, 15|23|4, 1|235|4, 1|23|45, 1|23|4|5, 145|2|3, 14|25|3, 14|2|35, 14|2|3|5, 15|24|3, 1|245|3, 1|24|35, 1|24|3|5, 15|2|34, 1|25|34, 1|2|345, 1|2|34|5, 15|2|3|4, 1|25|3|4, 1|2|35|4, 1|2|3|45, 1|2|3|4|5.
Triangle T(n,k) begins:
      1;
      1,     1;
      2,     1,     1;
      5,     4,     3,     1;
     15,    11,     9,     4,    1;
     52,    41,    35,    20,    5,    1;
    203,   162,   150,    90,   30,    6,   1;
    877,   715,   672,   455,  175,   42,   7,  1;
   4140,  3425,  3269,  2352, 1015,  280,  56,  8, 1;
  21147, 17722, 17271, 13132, 6237, 1890, 420, 72, 9, 1;
  ...
		

Crossrefs

Columns k=0-3 give: A000110, A000296(n+1), A327885, A328153.
T(2n,n) gives A276961.

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(n=0, 1, add(
          `if`(j=k, 0, b(n-j, k)*binomial(n-1, j-1)), j=1..n))
        end:
    T:= (n, k)-> b(n, 0)-`if`(k=0, 0, b(n, k)):
    seq(seq(T(n, k), k=0..n), n=0..11);
  • Mathematica
    b[n_, k_] := b[n, k] = If[n == 0, 1, Sum[If[j == k, 0, b[n - j,k] Binomial[ n - 1, j - 1]], {j, 1, n}]];
    T[n_, k_] := b[n, 0] - If[k == 0, 0, b[n, k]];
    Table[T[n, k], {n, 0, 11}, {k, 0, n}] // Flatten (* Jean-François Alcover, Apr 30 2020, after Alois P. Heinz *)

Formula

E.g.f. of column k: exp(exp(x)-1) - [k>0] * exp(exp(x)-1-x^k/k!).
T(n,0) - T(n,1) = A000296(n).

A328156 Number of set partitions of [2n] with distinct block sizes and one of the block sizes is n.

Original entry on oeis.org

1, 0, 0, 60, 280, 3780, 74844, 576576, 6949800, 110416020, 3319141540, 31333878576, 545777101324, 8349081650000, 196469122903200, 8108831645948160, 99934219113287400, 1961077012271694900, 39215221761564594900, 860948656518718429200, 25274389422461123124180
Offset: 0

Views

Author

Alois P. Heinz, Oct 05 2019

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(i*(i+1)/2 (2*n)!*(b(2*n$2, 0)-`if`(n=0, 0, b(2*n$2, n))):
    seq(a(n), n=0..22);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[i (i + 1)/2 < n, 0, If[n == 0, 1, If[i < 2, 0, b[n, i - 1, If[i == k, 0, k]]] + If[i == k, 0, b[n - i, Min[n - i, i - 1], k]/i!]]];
    a[n_] := (2n)! (b[2n, 2n, 0] - If[n == 0, 0, b[2n, 2n, n]]);
    a /@ Range[0, 22] (* Jean-François Alcover, May 02 2020, after Maple *)

Formula

a(n) = A327869(2n,n).

A328155 Number of set partitions of [n] with distinct block sizes and one of the block sizes is 3.

Original entry on oeis.org

0, 0, 0, 1, 4, 10, 60, 35, 336, 1848, 16080, 33825, 93280, 539396, 3856216, 49390250, 147478800, 708041160, 2354289744, 18196716309, 150847235040, 2615953578700, 9488756856040, 57565330671310, 296745669669768, 1435526275752900, 12231628020365000
Offset: 0

Views

Author

Alois P. Heinz, Oct 05 2019

Keywords

Crossrefs

Column k=3 of A327869.
Cf. A328153.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(i*(i+1)/2 b(n$2, 0)-b(n$2, 3):
    seq(a(n), n=0..29);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[i(i+1)/2 < n, 0, If[n == 0, 1, If[i < 2, 0, b[n, i - 1, If[i == k, 0, k]]] + If[i == k, 0, b[n - i, Min[n - i, i - 1], k]*Binomial[n, i]]]];
    a[n_] := b[n, n, 0] - b[n, n, 3];
    a /@ Range[0, 29] (* Jean-François Alcover, May 04 2020, after Maple *)

A327876 Number of set partitions of [n] with distinct block sizes and one of the block sizes is 1.

Original entry on oeis.org

0, 1, 0, 3, 4, 5, 66, 112, 456, 765, 15070, 31856, 150756, 663962, 1943046, 44316105, 127348864, 661449549, 3220447446, 20913769072, 68889553260, 2403704171190, 7894983374674, 51012052828947, 270186003789312, 1836634462055350, 13402212376611266
Offset: 0

Views

Author

Alois P. Heinz, Sep 28 2019

Keywords

Comments

Sum of multinomials M(n; lambda), where lambda ranges over all integer partitions of n into distinct parts and one part is 1.

Crossrefs

Column k=1 of A327869.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(i*(i+1)/2 b(n$2, 0)-b(n$2, 1):
    seq(a(n), n=0..29);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[i(i+1)/2 < n, 0, If[n == 0, 1, If[i < 2, 0, b[n, i - 1, If[i == k, 0, k]]] + If[i == k, 0, b[n - i, Min[n - i, i - 1], k] Binomial[n, i]]]];
    a[n_] := b[n, n, 0] - b[n, n, 1];
    a /@ Range[0, 29] (* Jean-François Alcover, Dec 18 2020, after Alois P. Heinz *)

Formula

a(1) = 1: 1.
a(2) = 0.
a(3) = 3: 12|3, 13|2, 1|23.
a(4) = 4: 123|4, 124|3, 134|2, 1|234.
a(5) = 5: 1234|5, 1235|4, 1245|3, 1345|2, 1|2345.
a(6) = 66: 12345|6, 12346|5, 12356|4, 123|45|6, 123|46|5, 123|4|56, 12456|3, 124|35|6, 124|36|5, 124|3|56, 125|34|6, 12|345|6, 126|34|5, 12|346|5, 125|36|4, 125|3|46, 126|35|4, 12|356|4, 126|3|45, 12|3|456, 13456|2, 134|25|6, 134|26|5, 134|2|56, 135|24|6, 13|245|6, 136|24|5, 13|246|5, 135|26|4, 135|2|46, 136|25|4, 13|256|4, 136|2|45, 13|2|456, 145|23|6, 14|235|6, 146|23|5, 14|236|5, 15|234|6, 1|23456, 16|234|5, 1|234|56, 156|23|4, 15|236|4, 16|235|4, 1|235|46, 1|236|45, 1|23|456, 145|26|3, 145|2|36, 146|25|3, 14|256|3, 146|2|35, 14|2|356, 156|24|3, 15|246|3, 16|245|3, 1|245|36, 1|246|35, 1|24|356, 156|2|34, 15|2|346, 1|256|34, 1|25|346, 16|2|345, 1|26|345.

A327881 Number of set partitions of [n] with distinct block sizes and one of the block sizes is 2.

Original entry on oeis.org

0, 0, 1, 3, 0, 10, 75, 126, 196, 1548, 15525, 39820, 161106, 358722, 3705884, 46623045, 142988280, 768721504, 3560215293, 12250746432, 144581799790, 2542575063630, 8955836934660, 55657973021431, 319349051391228, 1983548989621200, 7898257536096850
Offset: 0

Views

Author

Alois P. Heinz, Sep 28 2019

Keywords

Comments

Sum of multinomials M(n; lambda), where lambda ranges over all integer partitions of n into distinct parts and one part is 2.

Examples

			a(2) = 1: 12.
a(3) = 3: 12|3, 13|2, 1|23.
a(4) = 0.
a(5) = 10: 123|45, 124|35, 125|34, 12|345, 134|25, 135|24, 13|245, 145|23, 14|235, 15|234.
		

Crossrefs

Column k=2 of A327869.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(i*(i+1)/2 b(n$2, 0)-b(n$2, 2):
    seq(a(n), n=0..29);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[i(i+1)/2 < n, 0, If[n == 0, 1, If[i < 2, 0, b[n, i - 1, If[i == k, 0, k]]] + If[i == k, 0, b[n - i, Min[n - i, i - 1], k] Binomial[n, i]]]];
    a[n_] := b[n, n, 0] - b[n, n, 2];
    a /@ Range[0, 29] (* Jean-François Alcover, Dec 18 2020, after Alois P. Heinz *)
Showing 1-8 of 8 results.