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.

A077285 Number of partitions of n with designated summands.

Original entry on oeis.org

1, 1, 3, 5, 10, 15, 28, 41, 69, 102, 160, 231, 352, 498, 732, 1027, 1470, 2031, 2856, 3896, 5382, 7272, 9896, 13233, 17800, 23579, 31362, 41219, 54288, 70791, 92456, 119698, 155097, 199512, 256664, 328134, 419436, 533162, 677412, 856573, 1082284, 1361679
Offset: 0

Views

Author

Jorn B. Olsson (olsson(AT)math.ku.dk), Nov 26 2003

Keywords

Comments

Sum of products of multiplicities of parts in all partitions of n. The partitions of 4 are 4, 1+3, 2+2, 2+1+1, 1+1+1+1, the corresponding products are 1,1,2,2,4 and their sum is a(4) = 10. - Vladeta Jovovic, Feb 16 2005

Examples

			a(3)=5 because the partitions of 3 with designated summands are 3', 2'1', 1'11, 11'1, 111'.
1 + x + 3*x^2 + 5*x^3 + 10*x^4 + 15*x^5 + 28*x^6 + 41*x^7 + 69*x^8 + 102*x^9 + ...
		

Crossrefs

Cf. A102186 (partitions into odd parts with designated summands).

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          b(n, i-1) +add(b(n-i*j, i-1)*j, j=1..n/i)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..50);  # Alois P. Heinz, Feb 26 2013
  • Mathematica
    max = 50; f = Product[(1-x^i+x^(2*i))/(1-x^i)^2, {i, 1, max}]; s = Series[f, {x, 0, max}] // Normal; a[n_] := Coefficient[s, x, n]; Table[a[n], {n, 0, max}] (* Jean-François Alcover, May 06 2014, after Vladeta Jovovic *)
    nmax=100; CoefficientList[Series[Product[(1+x^(3*k)) / ((1-x^k) * (1-x^(2*k))), {k,1,nmax}], {x,0,nmax}], x] (* Vaclav Kotesovec, Nov 28 2015 *)
    QP = QPochhammer; s = QP[q^6]/(QP[q]*QP[q^2]*QP[q^3]) + O[q]^50; CoefficientList[s, q] (* Jean-François Alcover, Dec 01 2015, adapted from PARI *)
    Table[Total[l = Tally /@ IntegerPartitions@n;
    Table[x = l[[i]]; Product[x[[j, 2]], {j, Length[x]}], {i, Length[l]}]], {n, 0, 41}] (* Robert Price, Jun 06 2020 *)
  • PARI
    {a(n) = local(A); if( n<0, 0, A = x * O(x^n); polcoeff( eta(x^6 + A) / (eta(x + A) * eta(x^2 + A) * eta(x^3 + A)), n))} /* Michael Somos, Feb 05 2004 */

Formula

Expansion of eta(q^6) / (eta(q) * eta(q^2) * eta(q^3)) in powers of q. - Michael Somos, Feb 05 2004
Euler transform of period 6 sequence [ 1, 2, 2, 2, 1, 2, ...]. - Michael Somos, Feb 05 2004
G.f.: P(x)*P(x^2)*P(x^3)/P(x^6), where P(x)=Product_{k>0} 1/(1-x^k) is the partition generating function (A000041).
Equals EULER(DCONV(A000012, iEULER(A000027))).
G.f.: Product_{i>=1} (1-x^i+x^(2*i)) / (1-x^i)^2. - Vladeta Jovovic, Jan 16 2005
a(n) ~ 5^(3/4) * exp(Pi*sqrt(10*n)/3) / (2^(11/4) * 3^(3/2) * n^(5/4)). - Vaclav Kotesovec, Nov 28 2015
a(n) = Sum_{k>=1} k*A266477(n,k). - Alois P. Heinz, Dec 29 2015
G.f.: Product_{i>0} (1 + Sum_{j>0} j*x^(j*i)). - Seiichi Manyama, Oct 08 2017

Extensions

Edited and extended by Christian G. Bower, Jan 23 2004

A293422 The PDO_t(n) function (Number of tagged parts over all the partitions of n with designated summands in which all parts are odd).

Original entry on oeis.org

1, 2, 4, 6, 10, 16, 24, 36, 52, 74, 104, 144, 196, 264, 352, 468, 614, 800, 1036, 1332, 1704, 2168, 2744, 3456, 4331, 5408, 6724, 8328, 10278, 12640, 15496, 18936, 23072, 28030, 33960, 41040, 49470, 59488, 71368, 85428, 102042, 121632, 144692, 171792, 203584
Offset: 1

Views

Author

Seiichi Manyama, Oct 08 2017

Keywords

Examples

			n = 4                 n = 5                     n = 6
-------------------   -----------------------   ---------------------------
3'+ 1'        -> 2    5'                -> 1    5'+ 1'                -> 2
1'+ 1 + 1 + 1 -> 1    3'+ 1'+ 1         -> 2    3'+ 3                 -> 1
1 + 1'+ 1 + 1 -> 1    3'+ 1 + 1'        -> 2    3 + 3'                -> 1
1 + 1 + 1'+ 1 -> 1    1'+ 1 + 1 + 1 + 1 -> 1    3'+ 1'+ 1 + 1         -> 2
1 + 1 + 1 + 1'-> 1    1 + 1'+ 1 + 1 + 1 -> 1    3'+ 1 + 1'+ 1         -> 2
                      1 + 1 + 1'+ 1 + 1 -> 1    3'+ 1 + 1 + 1'        -> 2
                      1 + 1 + 1 + 1'+ 1 -> 1    1'+ 1 + 1 + 1 + 1 + 1 -> 1
                      1 + 1 + 1 + 1 + 1'-> 1    1 + 1'+ 1 + 1 + 1 + 1 -> 1
                                                1 + 1 + 1'+ 1 + 1 + 1 -> 1
                                                1 + 1 + 1 + 1'+ 1 + 1 -> 1
                                                1 + 1 + 1 + 1 + 1'+ 1 -> 1
                                                1 + 1 + 1 + 1 + 1 + 1'-> 1
-------------------   -----------------------   ---------------------------
a(4)          =  6.   a(5)              = 10.   a(6)                  = 16.
		

Crossrefs

Cf. A102186 (PDO(n)), A293421.

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[Product[(1-x^(2*k)) * (1-x^(3*k))^2 * (1-x^(12*k))^2 / ((1-x^k)^2 * (1-x^(6*k))), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Oct 15 2017 *)
  • Ruby
    def partition(n, min, max)
      return [[]] if n == 0
      [max, n].min.downto(min).flat_map{|i| partition(n - i, min, i).map{|rest| [i, *rest]}}
    end
    def A(n)
      partition(n, 1, n).select{|i| i.all?{|j| j.odd?}}.map{|a| a.each_with_object(Hash.new(0)){|v, o| o[v] += 1}.values}.map{|i| i.size * i.inject(:*)}.inject(:+)
    end
    def A293422(n)
      (1..n).map{|i| A(i)}
    end
    p A293422(40)

Formula

G.f.: q * Product_{k>0} ((1 - q^(2*k))*(1 - q^(3*k))^2*(1 - q^(12*k))^2)/((1 - q^k)^2*(1 - q^(6*k))).
a(n) ~ exp(sqrt(5*n)*Pi/3) / (3 * 2^(3/2) * 5^(1/4) * n^(1/4)). - Vaclav Kotesovec, Oct 15 2017

A293461 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of g.f. Product_{i>0} (1 + Sum_{j=1..k} j*x^(j*(2*i-1))).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 2, 1, 0, 1, 1, 2, 1, 1, 0, 1, 1, 2, 4, 1, 1, 0, 1, 1, 2, 4, 1, 3, 1, 0, 1, 1, 2, 4, 5, 3, 3, 1, 0, 1, 1, 2, 4, 5, 3, 6, 5, 2, 0, 1, 1, 2, 4, 5, 8, 6, 5, 6, 2, 0, 1, 1, 2, 4, 5, 8, 6, 9, 9, 4, 2, 0, 1, 1, 2, 4, 5, 8, 12, 9, 9, 13
Offset: 0

Views

Author

Seiichi Manyama, Oct 09 2017

Keywords

Examples

			Square array begins:
   1, 1, 1, 1, 1, ...
   0, 1, 1, 1, 1, ...
   0, 0, 2, 2, 2, ...
   0, 1, 1, 4, 4, ...
   0, 1, 1, 1, 5, ...
   0, 1, 3, 3, 3, ...
		

Crossrefs

Columns k=0..3 give A000007, A000700, A293304, A293463.
Rows n=0..1 give A000012, A057427.
Main diagonal gives A102186.
Cf. A290216.

Programs

  • Mathematica
    max = 12; A[n_, k_] := SeriesCoefficient[Product[(x*(-(k*x^((2*i - 1)*(k + 1) + 1)) - x^((2*i - 1)*(k + 1) + 1) + k*x^((2*i - 1)*(k + 1) + 2*i) + x^(2*i)))/(x^(2*i) - x)^2 + 1, {i, 1, max}], {x, 0, n}]; Flatten[ Table[ A[n - k, k], {n, 0, max}, {k, n, 0, -1}]] (* Jean-François Alcover, Oct 10 2017 *)

A293569 Partitions with designated summands in which no parts are multiples of 3.

Original entry on oeis.org

1, 1, 3, 4, 9, 12, 21, 29, 48, 64, 99, 132, 195, 257, 366, 480, 666, 864, 1173, 1511, 2016, 2576, 3384, 4296, 5574, 7027, 9015, 11296, 14355, 17880, 22527, 27908, 34896, 43008, 53406, 65508, 80844, 98711, 121128, 147272, 179784, 217704, 264489, 319064
Offset: 0

Views

Author

Seiichi Manyama, Oct 12 2017

Keywords

Examples

			n = 3        n = 4            n = 5
----------   --------------   ------------------
2'+ 1'       4'               5'
1'+ 1 + 1    2'+ 2            4'+ 1'
1 + 1'+ 1    2 + 2'           2'+ 2 + 1'
1 + 1 + 1'   2'+ 1'+ 1        2 + 2'+ 1'
             2'+ 1 + 1'       2'+ 1'+ 1 + 1
             1'+ 1 + 1 + 1    2'+ 1 + 1'+ 1
             1 + 1'+ 1 + 1    2'+ 1 + 1 + 1'
             1 + 1 + 1'+ 1    1'+ 1 + 1 + 1 + 1
             1 + 1 + 1 + 1'   1 + 1'+ 1 + 1 + 1
                              1 + 1 + 1'+ 1 + 1
                              1 + 1 + 1 + 1'+ 1
                              1 + 1 + 1 + 1 + 1'
----------   --------------   ------------------
a(3) = 4.    a(4) = 9.        a(5) = 12.
		

Crossrefs

Cf. A077285 (PD(n)), A102186 (PDO(n)), A293629.

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[Product[(1-x^(6*k))^2 / ( (1-x^k)^2 * (1+x^k) * (1+x^(9*k)) ), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Oct 13 2017 *)
  • Ruby
    def partition(n, min, max)
      return [[]] if n == 0
      [max, n].min.downto(min).flat_map{|i| partition(n - i, min, i).map{|rest| [i, *rest]}}
    end
    def A(k, n)
      partition(n, 1, n).select{|i| i.all?{|j| j % k > 0}}.map{|a| a.each_with_object(Hash.new(0)){|v, o| o[v] += 1}.values.inject(:*)}.inject(:+)
    end
    def A293569(n)
      [1] + (1..n).map{|i| A(3, i)}
    end
    p A293569(40)

Formula

Expansion of eta(q^6)^2 * eta(q^9) / (eta(q) * eta(q^2) * eta(q^18)) in powers of q.
a(n) ~ 5^(1/4) * exp(2*Pi*sqrt(5*n/3)/3) / (2 * 3^(7/4)* n^(3/4)). - Vaclav Kotesovec, Oct 13 2017

A293628 Expansion of Product_{k>0} ((1 - q^(2*k))^3*(1 - q^(6*k))*(1 - q^(12*k)))/((1 - q^k)^4*(1 - q^(4*k))).

Original entry on oeis.org

1, 4, 11, 28, 64, 136, 274, 528, 982, 1772, 3115, 5352, 9012, 14904, 24252, 38888, 61527, 96156, 148584, 227204, 344056, 516296, 768206, 1133952, 1661326, 2416816, 3492442, 5014932, 7157996, 10158672, 14339032, 20134888, 28133641, 39124028, 54161282, 74652260
Offset: 0

Views

Author

Seiichi Manyama, Oct 13 2017

Keywords

Crossrefs

Cf. A102186 (PDO(n)).

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[Product[(1+x^k)^3 * (1-x^(6*k)) * (1-x^(12*k)) / ((1-x^k) * (1-x^(4*k))), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Oct 15 2017 *)

Formula

a(n) = (1/2) * A102186(3*n+2).
a(n) ~ 5^(1/4) * exp(sqrt(5*n/3)*Pi) / (2^(7/2) * 3^(5/4) * n^(3/4)). - Vaclav Kotesovec, Oct 15 2017

A329163 Expansion of Product_{k>=1} 1 / (1 - Sum_{j>=1} j * x^(j*(2*k - 1))).

Original entry on oeis.org

1, 1, 3, 9, 22, 59, 156, 405, 1061, 2786, 7284, 19071, 49948, 130738, 342288, 896175, 2346134, 6142287, 16080852, 42100020, 110219366, 288558380, 755455128, 1977807393, 5177967900, 13556094631, 35490316938, 92914858431, 243254253904, 636847905903, 1667289469704, 4365020491362
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 06 2019

Keywords

Comments

Weigh transform of A032198.

Crossrefs

Programs

  • Mathematica
    nmax = 31; CoefficientList[Series[Product[1/(1 - Sum[j x^(j (2 k - 1)), {j, 1, nmax}]), {k, 1, nmax}], {x, 0, nmax}], x]
    nmax = 31; CoefficientList[Series[Product[1/(1 - x^(2 k - 1)/(1 - x^(2 k - 1))^2), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=1} 1 / (1 - x^(2*k - 1) / (1 - x^(2*k - 1))^2).
G.f.: Product_{k>=1} (1 + x^k)^A032198(k).
a(n) ~ c * phi^(2*n) / sqrt(5), where c = Product_{k>=2} 1/(1 - phi^(2 - 4*k)/(phi^(2 - 4*k) - 1)^2) = 1.07705428718361459418304978675229012... and phi = A001622 = (1+sqrt(5))/2 is the golden ratio. - Vaclav Kotesovec, Nov 07 2019
Showing 1-6 of 6 results.