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 1-6 of 6 results.

A326651 a(n) = Sum_{k>0} k * A326616(k,n).

Original entry on oeis.org

0, 1, 14, 243, 9692, 865445, 196868202, 122831606807, 219073289264824, 1139077903664789577, 17597009238919048388550, 821444189426979675481201211, 116802449602563244067365434335892, 50816512870344533477388136382624158445
Offset: 0

Views

Author

Alois P. Heinz, Sep 12 2019

Keywords

Crossrefs

Programs

  • Maple
    g:= proc(n) option remember; `if`(n=0, 0, numtheory[sigma](n)+g(n-1)) end:
    b:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0, add((t->
          b(n-t, min(n-t, i-1), k)*binomial(k, t))(i*j), j=0..n/i)))
        end:
    a:= k-> add(n*add(b(n$2, k-i)*(-1)^i*binomial(k, i), i=0..k), n=k..g(k)):
    seq(a(n), n=0..15);
  • Mathematica
    g[n_] := g[n] = If[n == 0, 0, DivisorSigma[1, n] + g[n - 1]];
    b[n_, i_, k_] := b[n, i, k] = If[n == 0, 1, If[i < 1, 0, Sum[With[{t = i*j}, b[n - t, Min[n - t, i - 1], k]*Binomial[k, t]], {j, 0, n/i}]]];
    a[k_] := Sum[n*Sum[b[n, n, k - i]*(-1)^i*Binomial[k, i], {i, 0, k}], {n, k, g[k]}];
    Table[a[n], {n, 0, 15}] (* Jean-François Alcover, Mar 24 2022, after Alois P. Heinz *)

Formula

a(n) = Sum_{k=n..A024916(n)} k * A326616(k,n) = Sum_{k=n..A024916(n)} k * A326617(k,n).

A178682 The number of functions f:{1,2,...,n}->{1,2,...,n} such that the number of elements that are mapped to m is divisible by m.

Original entry on oeis.org

1, 1, 2, 5, 13, 42, 150, 576, 2266, 9966, 47466, 237019, 1224703, 6429152, 35842344, 212946552, 1325810173, 8488092454, 55276544436, 362961569008, 2465240278980, 17538501945077, 130454679958312, 1002493810175093, 7838007702606372, 61789072382062638
Offset: 0

Views

Author

Geoffrey Critzer, Dec 25 2010

Keywords

Comments

a(n) is also the number of partitions of n where each block of part i with multiplicity j is marked with a word of length i*j over an n-ary alphabet whose letters appear in alphabetical order and all n letters occur exactly once in the partition. a(3) = 5: 3abc, 2ab1c, 2ac1b, 2bc1a, 111abc. There is a simple bijection between the marked partitions and the functions f. - Alois P. Heinz, Aug 30 2015

Examples

			a(3) = 5 because there are 5 such functions: (1,1,1), (1,2,2), (2,1,2), (2,2,1), (3,3,3).
G.f. = 1 + x + 2*x^2 + 5*x^3 + 13*x^4 + 42*x^5 + 150*x^6 + 576*x^7 + ...
		

Crossrefs

Main diagonal of A326500, A326616, A326617.
Row sums of A364285, A364310.

Programs

  • Magma
    m:=25; R:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!( (&*[(&+[x^(k*j)/Factorial(k*j): k in [0..m]]): j in [1..m]]) )); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, Jan 26 2019
    
  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(b(n-i*j, i-1)*binomial(n, i*j), j=0..n/i)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..30);  # Alois P. Heinz, Aug 30 2015
  • Mathematica
    Range[0,20]! CoefficientList[Series[Product[Sum[x^(j i)/(j i)!,{i,0,20}],{j,1,20}],{x,0,20}],x]
  • PARI
    m=30; my(x='x+O('x^m)); Vec(serlaplace(prod(j=1, m, sum(k=0,m, x^(k*j)/(k*j)!)))) \\ G. C. Greubel, Jan 26 2019
    
  • Sage
    m = 30; T = taylor(product(sum(x^(k*j)/factorial(k*j) for k in (0..m)) for j in (1..m)), x, 0, m); [factorial(n)*T.coefficient(x, n) for n in (0..m)] # G. C. Greubel, Jan 26 2019

Formula

E.g.f.: Product_{j>=1} Sum_{i>=0} x^(j*i)/(j*i)!.

Extensions

a(21)-a(25) from Alois P. Heinz, Aug 30 2015

A326617 Number T(n,k) of colored integer partitions of n using all colors of a k-set such that each block of part i with multiplicity j has a pattern of i*j distinct colors in increasing order; triangle T(n,k), k>=0, k<=n<=A024916(k), read by columns.

Original entry on oeis.org

1, 1, 2, 2, 1, 5, 9, 9, 10, 9, 3, 13, 44, 96, 152, 155, 124, 140, 160, 113, 48, 16, 4, 42, 225, 680, 1350, 2180, 3751, 6050, 7420, 6870, 5555, 5330, 6300, 6475, 5025, 3000, 1250, 250, 150, 1098, 4155, 11730, 30300, 69042, 127364, 188568, 249690, 365160, 584733
Offset: 0

Views

Author

Alois P. Heinz, Sep 12 2019

Keywords

Comments

T(n,k) is defined for all n>=0 and k>=0. The triangle displays only positive terms. All other terms are zero.

Examples

			T(3,2) = 2: 2a1b, 2b1a.
T(3,3) = 5: 3abc, 2ab1c, 2ac1b, 2bc1a, 111abc.
Triangle T(n,k) begins:
  1;
     1;
        2;
        2,  5;
        1,  9,  13;
            9,  44,   42;
           10,  96,  225,   150;
            9, 152,  680,  1098,    576;
            3, 155, 1350,  4155,   5201,   2266;
               124, 2180, 11730,  26642,  26904,   9966;
               140, 3751, 30300, 106281, 182000, 149832, 47466;
               ...
		

Crossrefs

Main diagonal gives A178682.
Row sums give A326648.
Column sums give A326650.
Cf. A000203, A024916, A326616 (this triangle read by rows), A326649, A326651.

Programs

  • Maple
    g:= proc(n) option remember; `if`(n=0, 0, numtheory[sigma](n)+g(n-1)) end:
    b:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0, add((t->
          b(n-t, min(n-t, i-1), k)*binomial(k, t))(i*j), j=0..n/i)))
        end:
    T:= (n, k)-> add(b(n$2, k-i)*(-1)^i*binomial(k, i), i=0..k):
    seq(seq(T(n, k), n=k..g(k)), k=0..6);
  • Mathematica
    g[n_] := g[n] = If[n == 0, 0, DivisorSigma[1, n] + g[n - 1]] ;
    b[n_, i_, k_] := b[n, i, k] = If[n == 0, 1, If[i < 1, 0, Sum[With[{t = i j}, b[n - t, Min[n - t, i - 1], k]*Binomial[k, t]], {j, 0, n/i}]]];
    T[n_, k_] := Sum[b[n, n, k - i]*(-1)^i*Binomial[k, i], {i, 0, k}];
    Table[Table[T[n, k], {n, k, g[k]}], {k, 0, 6}] // Flatten (* Jean-François Alcover, Mar 12 2021, after Alois P. Heinz *)

Formula

Sum_{k=A185283(n)..n} k * T(n,k) = A326649(n).
Sum_{n=k..A024916(k)} n * T(n,k) = A326651(k).

A326648 Number of colored integer partitions of n using all colors of an initial interval of the color palette such that each block of part i with multiplicity j has a pattern of i*j distinct colors in increasing order.

Original entry on oeis.org

1, 1, 2, 7, 23, 95, 481, 2515, 13130, 77546, 519770, 3641724, 25931163, 185418629, 1411248697, 11735504788, 103340890753, 931471895697, 8448978391755, 76541843977198, 715994685630321, 7110500945450780, 74757652968961770, 815423663501064107, 9012653697655462141
Offset: 0

Views

Author

Alois P. Heinz, Sep 12 2019

Keywords

Crossrefs

Row sums of A326616 and of A326617.

Programs

  • Maple
    g:= proc(n) option remember; `if`(n=0, 0, numtheory[sigma](n)+g(n-1)) end:
    h:= proc(n) option remember; local k; for k from
          `if`(n=0, 0, h(n-1)) do if g(k)>=n then return k fi od
        end:
    b:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1 or k b(n-t, min(n-t, i-1), k)*binomial(k, t))(i*j), j=0..n/i)))
        end:
    a:= n-> add(add(b(n$2, k-i)*(-1)^i*binomial(k, i), i=0..k), k=h(n)..n):
    seq(a(n), n=0..25);
  • Mathematica
    g[n_] := g[n] = If[n == 0, 0, DivisorSigma[1, n] + g[n-1]];
    h[n_] := h[n] = Module[{k}, For[k = If[n == 0, 0, h[n-1]], True, k++, If[g[k] >= n, Return[k]]]];
    b[n_, i_, k_] := b[n, i, k] = If[n==0, 1, If[i<1 || k < h[n], 0, Sum[With[ {t = i j}, b[n-t, Min[n-t, i-1], k] Binomial[k, t]], {j, 0, n/i}]]];
    a[n_] := Sum[b[n, n, k-i] (-1)^i Binomial[k, i], {k, h[n], n}, {i, 0, k}];
    a /@ Range[0, 25] (* Jean-François Alcover, Dec 09 2020, after Alois P. Heinz *)

A326649 Total number of colors in all colored integer partitions of n using all colors of an initial interval of the color palette such that each block of part i with multiplicity j has a pattern of i*j distinct colors in increasing order.

Original entry on oeis.org

0, 1, 4, 19, 81, 413, 2439, 14655, 86844, 573196, 4224230, 32280154, 249433713, 1925416359, 15732592327, 139542345546, 1304524118159, 12445507282579, 119198874300879, 1137647406084952, 11183828252431175, 116368970786569604, 1278400213028604214
Offset: 0

Views

Author

Alois P. Heinz, Sep 12 2019

Keywords

Crossrefs

Programs

  • Maple
    g:= proc(n) option remember; `if`(n=0, 0, numtheory[sigma](n)+g(n-1)) end:
    h:= proc(n) option remember; local k; for k from
          `if`(n=0, 0, h(n-1)) do if g(k)>=n then return k fi od
        end:
    b:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1 or k b(n-t, min(n-t, i-1), k)*binomial(k, t))(i*j), j=0..n/i)))
        end:
    a:= n-> add(k*add(b(n$2, k-i)*(-1)^i*binomial(k, i), i=0..k), k=h(n)..n):
    seq(a(n), n=0..25);
  • Mathematica
    g[n_] := g[n] = If[n == 0, 0, DivisorSigma[1, n] + g[n - 1]];
    h[n_] := h[n] = Module[{k}, For[k = If[n == 0, 0, h[n - 1]], True, k++, If[g[k] >= n, Return [k]]]];
    b[n_, i_, k_] := b[n, i, k] = If[n==0, 1, If[i<1 || kJean-François Alcover, Dec 09 2020, after Alois P. Heinz *)

Formula

a(n) = Sum_{k=A185283(n)..n} k * A326616(n,k) = Sum_{k=A185283(n)..n} k * A326617(n,k).

A326650 Number of colored integer partitions using all colors of an n-set such that each block of part i with multiplicity j has a pattern of i*j distinct colors in increasing order.

Original entry on oeis.org

1, 1, 5, 45, 1065, 61753, 9705069, 4394516773, 5931440509137, 24154079629381105, 300121111037478706517, 11510717148660156841731485, 1369013994385630011763634779641, 505666129597215709912984823873504809, 582167751341290615329122568805084839847101
Offset: 0

Views

Author

Alois P. Heinz, Sep 12 2019

Keywords

Crossrefs

Column sums of A326616 and of A326617.

Programs

  • Maple
    g:= proc(n) option remember; `if`(n=0, 0, numtheory[sigma](n)+g(n-1)) end:
    b:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0, add((t->
          b(n-t, min(n-t, i-1), k)*binomial(k, t))(i*j), j=0..n/i)))
        end:
    a:= k-> add(add(b(n$2, k-i)*(-1)^i*binomial(k, i), i=0..k), n=k..g(k)):
    seq(a(n), n=0..15);
  • Mathematica
    g[n_] := g[n] = If[n == 0, 0, DivisorSigma[1, n] + g[n - 1]];
    b[n_, i_, k_] := b[n, i, k] = If[n==0, 1, If[i < 1, 0, Sum[With[{t = i j}, b[n - t, Min[n - t, i - 1], k] Binomial[k, t]], {j, 0, n/i}]]];
    a[k_] := Sum[b[n, n, k-i] (-1)^i Binomial[k, i], {n, k, g[k]}, {i, 0, k}];
    a /@ Range[0, 15] (* Jean-François Alcover, Dec 09 2020, after Alois P. Heinz *)
Showing 1-6 of 6 results.