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.

Previous Showing 11-20 of 47 results. Next

A028417 Sum over all n! permutations of n elements of minimum lengths of cycles.

Original entry on oeis.org

1, 3, 10, 45, 236, 1505, 10914, 90601, 837304, 8610129, 96625970, 1184891081, 15665288484, 223149696601, 3394965018886, 55123430466945, 948479737691504, 17289345305870561, 332019600921360594, 6713316975465246889, 142321908843254560540, 3161718732648662557161
Offset: 1

Views

Author

Joe Keane (jgk(AT)jgk.org)

Keywords

Crossrefs

Cf. A005225.
Column k=1 of A322383.

Programs

  • Maple
    b:= proc(n, m) option remember; `if`(n=0, m, add((j-1)!*
          b(n-j, min(m,j))*binomial(n-1, j-1), j=1..n))
        end:
    a:= n-> b(n, infinity):
    seq(a(n), n=1..25);  # Alois P. Heinz, May 14 2016
  • Mathematica
    Drop[Apply[Plus,Table[nn=25;Range[0,nn]!CoefficientList[Series[Exp[Sum[ x^i/i,{i,n,nn}]]-1,{x,0,nn}],x],{n,1,nn}]],1] (* Geoffrey Critzer, Jan 10 2013 *)
    b[n_, m_] := b[n, m] = If[n == 0, m, Sum[(j-1)! b[n-j, Min[m, j]]* Binomial[n-1, j-1], {j, n}]];
    a[n_] := b[n, Infinity];
    Array[a, 25] (* Jean-François Alcover, Apr 21 2020, after Alois P. Heinz *)

Formula

E.g.f.: Sum[k>0, -1+ exp(Sum(j>=k, x^j/j))]. - Vladeta Jovovic, Jul 26 2004
a(n) = Sum_{k=1..n} k * A145877(n,k). - Alois P. Heinz, Jul 28 2014

Extensions

More terms from Vladeta Jovovic, Sep 19 2002

A092265 Sum of smallest parts of all partitions of n into distinct parts.

Original entry on oeis.org

1, 2, 4, 5, 8, 10, 14, 16, 23, 26, 34, 40, 50, 58, 74, 83, 102, 120, 142, 164, 198, 226, 266, 308, 359, 412, 482, 548, 634, 730, 834, 950, 1094, 1240, 1416, 1609, 1826, 2068, 2350, 2648, 2994, 3382, 3806, 4280, 4826, 5408, 6070, 6806, 7619, 8522, 9534, 10632
Offset: 1

Views

Author

Vladeta Jovovic, Feb 14 2004

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1,
         `if`(i>n, 0, b(n,i+1)+b(n-i, i+1)))
        end:
    a:= n-> add(j*b(n-j, j+1), j=1..n):
    seq(a(n), n=1..80);  # Alois P. Heinz, Feb 03 2016
  • Mathematica
    b[n_, i_] := b[n, i] = If[n == 0, 1, If[i > n, 0, b[n, i + 1] + b[n - i, i + 1]]]; a[n_] := Sum[j*b[n - j, j + 1], {j, 1, n}]; Table[a[n], {n, 1, 80}] (* Jean-François Alcover, Jan 21 2017, after Alois P. Heinz *)

Formula

G.f.: Sum_{n >= 1} (-1 + Product_{k >= n} 1 + x^k).
G.f.: Sum_{n >= 1} n*x^n*Product_{k >= n+1} (1 + x^k). - Joerg Arndt, Jan 29 2011
G.f.: Sum_{k >= 1} x^(k*(k+1)/2)/(1 - x^k)/Product_{i = 1..k} (1 - x^i). - Vladeta Jovovic, Aug 10 2004
Conjecture: a(n) = A034296(n) + A237665(n+1). - George Beck, May 06 2017
a(n) ~ exp(Pi*sqrt(n/3)) / (2 * 3^(1/4) * n^(3/4)). - Vaclav Kotesovec, May 20 2018

Extensions

More terms from Pab Ter (pabrlos(AT)yahoo.com), May 25 2004

A097939 Sum of the smallest parts of all compositions of n.

Original entry on oeis.org

1, 3, 6, 12, 22, 42, 79, 151, 291, 566, 1106, 2175, 4293, 8499, 16864, 33523, 66727, 132958, 265137, 529050, 1056169, 2109282, 4213710, 8419697, 16827079, 33634489, 67237513, 134424624, 268768414, 537407062, 1074605619, 2148875961, 4297212424, 8593556211, 17185713097, 34369170909
Offset: 1

Views

Author

Vladeta Jovovic, Sep 05 2004

Keywords

Comments

Sums of the antidiagonals of A099238. - Paul Barry, Oct 08 2004

Crossrefs

Programs

  • Maple
    A097939:=n->add(add(binomial(n-r*(k+1)-1,k), k=0..floor((n-r-1)/(r+1))), r=0..n-1): seq(A097939(n), n=1..50); # Wesley Ivan Hurt, Dec 03 2016
    # second Maple Program:
    b:= proc(n, m) option remember; `if`(n=0, m,
          add(b(n-j, min(j, m)), j=1..n))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=1..40);  # Alois P. Heinz, Jul 26 2020
  • Mathematica
    Drop[ CoefficientList[ Series[ Sum[x^k/(1 - x - x^k), {k, 50}], {x, 0, 35}], x], 1] (* Robert G. Wilson v, Sep 08 2004 *)
  • PARI
    N=66; x='x+O('x^N);
    gf= sum(k=1,N, x^k/(1-x-x^k) );
    Vec(gf)
    /* Joerg Arndt, Jan 01 2013 */
    
  • PARI
    {a(n)=polcoeff(sum(m=1,n,x^m*sumdiv(m,d,1/(1-x +x*O(x^n))^d) ),n)}

Formula

G.f.: Sum_{k>=1} x^k/(1-x-x^k).
a(n) = Sum_{r=0..n-1} Sum_{k=0..floor((n-r-1)/(r+1))} binomial(n-r(k+1)-1, k). - Paul Barry, Oct 08 2004
G.f.: (1-x)^2 * Sum_{k>=1} k*x^k/((x^k+x-1)*(x^(k+1)+x-1)). - Vladeta Jovovic, Apr 23 2006
G.f.: Sum_{k>=1} x^k/((1-x)^k*(1-x^k)). - Vladeta Jovovic, Mar 02 2008
G.f.: Sum_{n>=1} a*x^n/(1-a*x^n) (generalized Lambert series) where a=1/(1-x). - Joerg Arndt, Jan 30 2011
G.f.: Sum_{n>=1} (a*x)^n/(1-x^n) where a=1/(1-x). - Joerg Arndt, Jan 01 2013
G.f.: Sum_{n>=1} x^n * Sum_{d|n} 1/(1-x)^d. - Paul D. Hanna, Jul 18 2013
a(n) ~ 2^(n-1). - Vaclav Kotesovec, Oct 28 2014

Extensions

More terms from Robert G. Wilson v, Sep 08 2004

A194437 Triangle read by rows: T(n,k) = sum of parts in the k-th region of n.

Original entry on oeis.org

1, 1, 3, 1, 3, 5, 1, 3, 5, 2, 9, 1, 3, 5, 2, 9, 3, 12, 1, 3, 5, 2, 9, 3, 12, 2, 6, 3, 20, 1, 3, 5, 2, 9, 3, 12, 2, 6, 3, 20, 3, 7, 4, 25, 1, 3, 5, 2, 9, 3, 12, 2, 6, 3, 20, 3, 7, 4, 25, 2, 6, 3, 13, 5, 4, 38, 1, 3, 5, 2, 9, 3, 12, 2, 6, 3, 20, 3, 7
Offset: 1

Views

Author

Omar E. Pol, Nov 27 2011

Keywords

Examples

			Triangle begins:
1;
1,3;
1,3,5;
1,3,5,2,9;
1,3,5,2,9,3,12;
1,3,5,2,9,3,12,2,6,3,20;
1,3,5,2,9,3,12,2,6,3,20,3,7,4,25;
1,3,5,2,9,3,12,2,6,3,20,3,7,4,25,2,6,3,13,5,4,38;
...
Row n has length A000041(n). Row sums give A066186. Right border gives A046746. Records in every row give A046746. Rows converge to A186412.
		

Crossrefs

A182715 Triangle read by rows in which row n lists in nonincreasing order the smallest part of every partition of n.

Original entry on oeis.org

0, 1, 2, 1, 3, 1, 1, 4, 2, 1, 1, 1, 5, 2, 1, 1, 1, 1, 1, 6, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 7, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 8, 4, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 4, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
Offset: 0

Views

Author

Omar E. Pol, Dec 01 2010

Keywords

Comments

Triangle read by rows in which row n lists the smallest parts of all partitions of n in the order produced by the shell model of partitions of A138121.
Also, row n lists the "filler parts" of all partition of n. For more information see A182699.
Row n has length A000041(n). Row sums give A046746. Column 1 gives A001477. The last A000041(n-1) terms of row n are ones, n >= 1.

Examples

			For row 10, see the illustration of the link.
Triangle begins:
  0,
  1,
  2,1,
  3,1,1,
  4,2,1,1,1,
  5,2,1,1,1,1,1,
  6,3,2,2,1,1,1,1,1,1,1,
  7,3,2,2,1,1,1,1,1,1,1,1,1,1,1,
  8,4,3,2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
  9,4,3,3,2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
  ...
		

Crossrefs

Mirror of triangle A196931.

Extensions

Name simplified and more terms from Omar E. Pol, Oct 21 2011

A196931 Triangle read by rows in which row n lists in nondecreasing order the smallest part of every partition of n.

Original entry on oeis.org

0, 1, 1, 2, 1, 1, 3, 1, 1, 1, 2, 4, 1, 1, 1, 1, 1, 2, 5, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 6, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 7, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 3, 4, 8, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
Offset: 0

Views

Author

Omar E. Pol, Oct 21 2011

Keywords

Comments

If n >= 1, row n lists the smallest parts of every partition of n in the order produced by the shell model of partitions of A135010, hence row n lists the parts of the last section of the set of partitions of n, except the emergent parts (See A182699).
Row n has length A000041(n). Row sums give A046746. Right border of triangle gives A001477. Row n starts with A000041(n-1) ones, n >= 1.

Examples

			Written as a triangle:
  0,
  1,
  1,2,
  1,1,3,
  1,1,1,2,4,
  1,1,1,1,1,2,5,
  1,1,1,1,1,1,1,2,2,3,6
  1,1,1,1,1,1,1,1,1,1,1,2,2,3,7,
  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,3,4,8,
  ...
		

Crossrefs

A116686 Total number of parts smaller than the largest part, in all partitions of n.

Original entry on oeis.org

0, 0, 1, 3, 8, 15, 29, 48, 79, 123, 188, 276, 404, 575, 808, 1122, 1540, 2089, 2811, 3748, 4958, 6519, 8504, 11034, 14231, 18268, 23312, 29638, 37486, 47245, 59279, 74140, 92347, 114703, 141933, 175174, 215478, 264407, 323448, 394788, 480509, 583609
Offset: 1

Views

Author

Emeric Deutsch, Feb 23 2006

Keywords

Comments

Also, sum over all partitions of n of the difference between the largest part and the smallest part. - Franklin T. Adams-Watters, Feb 29 2008
Row sums of A244966. - Omar E. Pol, Jul 19 2014

Examples

			a(5) = 8 because the partitions of 5 are [5], [4,(1)], [3,(2)], [3,(1),(1)], [2,2,(1)], [2,(1),(1),(1)] and [1,1,1,1,1], containing a total of 8 parts that are smaller than the largest part (shown between parentheses).
		

Crossrefs

Programs

  • Maple
    f:=sum(x^i*sum(x^j/(1-x^j),j=1..i-1)/product(1-x^q,q=1..i),i=2..55): fser:=series(f,x=0,50): seq(coeff(fser,x^n),n=1..47);
  • Mathematica
    Table[Length[Flatten[Rest[Split[#]]&/@Select[IntegerPartitions[n], #[[1]]> #[[-1]]&]]],{n,50}] (* Harvey P. Dale, Jul 26 2016 *)

Formula

a(n) = Sum_{k>=0} k*A116685(n,k).
G.f.: Sum_{i>=1} (x^i*(Sum_{j=1..i-1} x^j/(1-x^j))/(Product_{q=1..i} (1-x^q))).
a(n) = A006128(n) - A046746(n). - Vladeta Jovovic, Feb 24 2006
a(n) = A211870(n) + A211881(n). - Alois P. Heinz, Feb 13 2013

A210952 Triangle read by rows: T(n,k) = sum of all parts of the k-th column of the partitions of n but with the partitions aligned to the right margin.

Original entry on oeis.org

1, 1, 3, 1, 3, 5, 1, 3, 7, 9, 1, 3, 7, 12, 12, 1, 3, 7, 14, 21, 20, 1, 3, 7, 14, 24, 31, 25, 1, 3, 7, 14, 26, 40, 47, 38, 1, 3, 7, 14, 26, 43, 61, 66, 49, 1, 3, 7, 14, 26, 45, 70, 92, 93, 69, 1, 3, 7, 14, 26, 45, 73, 106, 130, 124, 87, 1, 3, 7, 14
Offset: 1

Views

Author

Omar E. Pol, Apr 22 2012

Keywords

Examples

			For n = 6 the illustration shows the partitions of 6 aligned to the right margin and below the sums of the columns:
.
.                      6
.                  3 + 3
.                  4 + 2
.              2 + 2 + 2
.                  5 + 1
.              3 + 2 + 1
.              4 + 1 + 1
.          2 + 2 + 1 + 1
.          3 + 1 + 1 + 1
.      2 + 1 + 1 + 1 + 1
.  1 + 1 + 1 + 1 + 1 + 1
-------------------------
.  1,  3,  7, 14, 21, 20
.
So row 6 lists 1, 3, 7, 14, 21, 20.
Triangle begins:
1;
1, 3;
1, 3, 5;
1, 3, 7,  9;
1, 3, 7, 12, 12;
1, 3, 7, 14, 21, 20;
1, 3, 7, 14, 24, 31, 25;
1, 3, 7, 14, 26, 40, 47, 38;
1, 3, 7, 14, 26, 43, 61, 66, 49;
1, 3, 7, 14, 26, 45, 70, 92, 93, 69:
		

Crossrefs

Mirror of triangle A206283. Rows sums give A066186. Rows converge to A014153. Right border gives A046746, >= 1.

Formula

T(n,k) = Sum_{j=1..n} A210953(j,k). - Omar E. Pol, May 26 2012

A222044 Sum of smallest parts of all partitions of n into an odd number of parts.

Original entry on oeis.org

0, 1, 2, 4, 5, 8, 11, 15, 19, 28, 35, 47, 61, 80, 102, 136, 168, 218, 276, 350, 437, 556, 686, 860, 1063, 1321, 1620, 2005, 2443, 2998, 3649, 4445, 5377, 6531, 7863, 9496, 11398, 13694, 16373, 19603, 23347, 27834, 33058, 39259, 46467, 55020, 64914, 76599
Offset: 0

Views

Author

Alois P. Heinz, Feb 06 2013

Keywords

Comments

a(n) + A222045(n) = A046746(n).
a(n) - A222045(n) = A222046(n).

Examples

			a(6) = 11: partitions of 6 into an odd number of parts are [2,1,1,1,1], [2,2,2], [3,2,1], [4,1,1], [6], sum of smallest parts is 1+2+1+1+6 = 11.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember;
          [`if`(n=i, n, 0), 0]+`if`(i<1, [0, 0], b(n, i-1)+
           `if`(n [l[2], l[1]])(b(n-i, i))))
        end:
    a:= n-> b(n, n)[1]:
    seq(a(n), n=0..60);
  • Mathematica
    b[n_, i_] := b[n, i] = {If[n==i, n, 0], 0} + If[i<1, {0, 0}, b[n, i-1] + If[nJean-François Alcover, Feb 03 2017, translated from Maple *)
    Table[Total[Min/@Select[IntegerPartitions[n],OddQ[Length[#]]&]],{n,0,50}] (* Harvey P. Dale, Jul 05 2019 *)

Formula

a(n) ~ exp(Pi*sqrt(2*n/3)) / (8*sqrt(3)*n). - Vaclav Kotesovec, Jul 06 2019

A222045 Sum of smallest parts of all partitions of n into an even number of parts.

Original entry on oeis.org

0, 0, 1, 1, 4, 4, 9, 10, 19, 21, 34, 40, 62, 72, 103, 124, 173, 207, 279, 337, 445, 538, 694, 842, 1077, 1299, 1634, 1977, 2464, 2969, 3669, 4411, 5410, 6488, 7896, 9447, 11442, 13640, 16421, 19536, 23411, 27761, 33124, 39174, 46554, 54915, 65008, 76485, 90258
Offset: 0

Views

Author

Alois P. Heinz, Feb 06 2013

Keywords

Comments

A222044(n) + a(n) = A046746(n).
A222044(n) - a(n) = A222046(n).

Examples

			a(6) = 9: partitions of 6 into an even number of parts are [1,1,1,1,1,1], [2,2,1,1], [3,1,1,1], [3,3], [4,2], [5,1], sum of smallest parts is 1+1+1+3+2+1 = 9.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember;
          [`if`(n=i, n, 0), 0]+`if`(i<1, [0, 0], b(n, i-1)+
           `if`(n [l[2], l[1]])(b(n-i, i))))
        end:
    a:= n-> b(n, n)[2]:
    seq(a(n), n=0..60);
  • Mathematica
    b[n_, i_] := b[n, i] = {If[n==i, n, 0], 0} + If[i<1, {0, 0}, b[n, i-1] + If[nJean-François Alcover, Feb 03 2017, translated from Maple *)

Formula

a(n) ~ exp(Pi*sqrt(2*n/3)) / (8*sqrt(3)*n). - Vaclav Kotesovec, Jul 06 2019
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