A036469 -id:A036469 - cp's OEIS frontend

A201377 Triangle read by rows: T(n,k) (0 <= k <= n) is the number of partitions of (n,k) into a sum of distinct pairs.

1, 1, 2, 1, 3, 5, 2, 5, 9, 17, 2, 7, 14, 27, 46, 3, 10, 21, 42, 74, 123, 4, 14, 31, 64, 116, 197, 323, 5, 19, 44, 93, 174, 303, 506, 809, 6, 25, 61, 132, 254, 452, 769, 1251, 1966, 8, 33, 83, 185, 363, 659, 1141, 1885, 3006, 4660

Offset: 0

Reinhard Zumkeller, Nov 30 2011

By analogy with ordinary partitions into distinct parts (A000009). The empty partition gives T(0,0)=1 by definition. A201376 and A054242 give partitions of pairs into sums of not necessarily distinct pairs.

Parts (i,j) are "positive" in the sense that min {i,j} >= 0 and max {i,j} >0. The empty partition of (0,0) is counted as 1.

			Partitions of (2,1) into distinct positive pairs, T(2,1) = 3:
(2,1),
(2,0) + (0,1),
(1,1) + (1,0);
Partitions of (2,2) into distinct positive pairs, T(2,2) = 5:
(2,2),
(2,1) + (0,1),
(2,0) + (0,2),
(1,2) + (1,0),
(1,1) + (1,0) + (0,1).
First ten rows of triangle:
0:                      1
1:                    1  2
2:                  1  3  5
3:                2  5  9  17
4:              2  7  14  27  46
5:            3  10  21  42  74  123
6:          4  14  31  64  116  197  323
7:        5  19  44  93  174  303  506  809
8:      6  25  61  132  254  452  769  1251  1966
9:    8  33  83  185  363  659  1141  1885  3006  4660

Alois P. Heinz, Rows n = 0..80, flattened
Reinhard Zumkeller, Haskell programs for A054225, A054242, A201376, A201377

T(n,0) = A000009(n);
T(1,0) = A036469(0);  T(n,1) = A036469(n) for n > 0.
See A054242 for another version.
Cf. A000009, A054225, A201376.
T(n,n) = A219554(n). Row sums give: A219557. - Alois P. Heinz, Nov 22 2012

Haskell
```
-- see link.
```

nmax = 10;
f[x_, y_] := Product[1 + x^n y^k, {n, 0, nmax}, {k, 0, nmax}]/2;
se = Series[f[x, y], {x, 0, nmax}, {y, 0, nmax}];
coes = CoefficientList[se, {x, y}];
t[n_ /; n >= 0, k_] /; 0 <= k <= n := coes[[n-k+1, k+1]];
T[n_, k_] := t[n+k, k];
Table[T[n, k], {n, 0, nmax}, {k, 0, n}] // Flatten (* Jean-François Alcover, Nov 08 2021 *)

For g.f. see A054242.

Entry revised by N. J. A. Sloane, Nov 30 2011

A219554 Number of bipartite partitions of (n,n) into distinct pairs.

Original entry on oeis.org

1, 2, 5, 17, 46, 123, 323, 809, 1966, 4660, 10792, 24447, 54344, 118681, 254991, 539852, 1127279, 2323849, 4733680, 9535079, 19005282, 37507802, 73333494, 142112402, 273092320, 520612305, 984944052, 1849920722, 3450476080, 6393203741, 11770416313, 21538246251

Offset: 0

Alois P. Heinz, Nov 22 2012

Number of factorizations of p^n*q^n into distinct factors where p, q are distinct primes.
From Vaclav Kotesovec, Feb 05 2016: (Start)
Formula (15) in the article by S. M. Luthra: "Partitions of bipartite numbers when the summands are unequal", p. 376, is incorrect. The similar error is also in the article by F. C. Auluck: "On partitions of bipartite numbers" (see A002774).
The correct formula (15) is q(m, n) ~ c/(2*sqrt(3)*Pi) * exp(3*c*(m*n)^(1/3) + 3*d*(m^(2/3)/n^(1/3) + n^(2/3)/m^(1/3)) - 3*log(2)/4 + (m/n + n/m)*log(2)/12 + 3*d^2/c - 3*d^2*(m/n + n/m)/c - 2*log(m*n)/3), where m and n are of the same order, c = (3/4*Zeta(3))^(1/3), d = Zeta(2)/(12*c).
If m = n then q(m,n) = a(n).
For the asymptotic formula for fixed m see A054242.
(End)

			a(0) = 1: [].
a(1) = 2: [(1,1)], [(1,0),(0,1)].
a(2) = 5: [(2,2)], [(2,1),(0,1)], [(2,0),(0,2)], [(1,2),(1,0)], [(1,1),(1,0),(0,1)].

Alois P. Heinz and Vaclav Kotesovec, Table of n, a(n) for n = 0..400 (terms 0..100 from Alois P. Heinz)
S. M. Luthra, Partitions of bipartite numbers when the summands are unequal, Proceedings of the Indian National Science Academy, vol. 23, 1957, issue 5A, p. 370-376. [broken link]

Column k=2 of A219585.
Cf. A002774, A219560, A219561, A219565.
Cf. A054242, A000009, A036469, A268345, A268346, A268347, A268348.

(* This program is not convenient for a large number of terms *)
a[n_] := If[n == 0, 1, (1/2) Coefficient[Product[O[x]^(n+1) + O[y]^(n+1) + (1 + x^i y^j ), {i, 0, n}, {j, 0, n}] // Normal, (x y)^n]];
a /@ Range[0, 31] (* Jean-François Alcover, Jun 26 2013, updated Sep 16 2019 *)
nmax = 20; p = 1; Do[Do[p = Expand[p*(1 + x^i*y^j)]; If[i*j != 0, p = Select[p, (Exponent[#, x] <= nmax) && (Exponent[#, y] <= nmax) &]], {i, 0, nmax}], {j, 0, nmax}]; p = Select[p, Exponent[#, x] == Exponent[#, y] &]; Flatten[{1, Table[Coefficient[p, x^n*y^n]/2, {n, 1, nmax}]}] (* Vaclav Kotesovec, Jan 15 2016 *)

a(n) = [x^n*y^n] 1/2 * Product_{i,j>=0} (1+x^i*y^j).
a(n) = A054242(2*n,n) = A201377(n,n).
a(n) ~ Zeta(3)^(1/3) * exp(3^(4/3) * Zeta(3)^(1/3) * n^(2/3) / 2^(2/3) + Pi^2 * n^(1/3) / (6^(4/3) * Zeta(3)^(1/3)) - Pi^4/(1296*Zeta(3))) / (2^(9/4) * 3^(1/6) * Pi * n^(4/3)). - Vaclav Kotesovec, Jan 31 2016

A026906 Number of sums S of distinct positive integers satisfying S <= n.

Original entry on oeis.org

1, 2, 4, 6, 9, 13, 18, 24, 32, 42, 54, 69, 87, 109, 136, 168, 206, 252, 306, 370, 446, 535, 639, 761, 903, 1068, 1260, 1482, 1738, 2034, 2374, 2764, 3212, 3724, 4309, 4977, 5737, 6601, 7583, 8696, 9956, 11382, 12992, 14808, 16856

Offset: 1

Clark Kimberling

nonn

			G.f. = x + 2*x^2 + 4*x^3 + 6*x^4 + 9*x^5 + 13*x^6 + 18*x^7 + 24*x^8 + 32*x^9 + ...

Vaclav Kotesovec, Table of n, a(n) for n = 1..10000

Partial sums of A000009.

Cf. A000070.

Table[ Sum[ PartitionsQ[k], {k, 1, n}], {n, 1, 50}]

a(n) ~ exp(Pi*sqrt(n/3)) * 3^(1/4) / (2*Pi*n^(1/4)) * (1 + (18+13*Pi^2) / (48*Pi*sqrt(3*n))). - Vaclav Kotesovec, Oct 25 2016
a(n) = A036469(n) - 1. - Vaclav Kotesovec, Oct 26 2016
G.f.: -1/(1 - x) + (1/(1 - x))*Product_{k>=1} (1 + x^k). - Ilya Gutkovskiy, Dec 25 2016

A341062 Sequence whose partial sums give A000005.

Original entry on oeis.org

1, 1, 0, 1, -1, 2, -2, 2, -1, 1, -2, 4, -4, 2, 0, 1, -3, 4, -4, 4, -2, 0, -2, 6, -5, 1, 0, 2, -4, 6, -6, 4, -2, 0, 0, 5, -7, 2, 0, 4, -6, 6, -6, 4, 0, -2, -2, 8, -7, 3, -2, 2, -4, 6, -4, 4, -4, 0, -2, 10, -10, 2, 2, 1, -3, 4, -6, 4, -2, 4, -6, 10, -10, 2, 2, 0, -2, 4, -6, 8, -5, -1, -2, 10, -8, 0, 0, 4, -6, 10

Offset: 1

Omar E. Pol, Feb 04 2021

Essentially a duplicate of A051950.
Convolved with A000041 gives A138137.
Convolved with A000027 gives the nonzero terms of A006218.
Convolved with A000070 gives the nonzero terms of A006128.
Convolved with A014153 gives the nonzero terms of A284870.
Convolved with A036469 gives the nonzero terms of A305082.
Convolved with the nonzero terms of A006218 gives A055507.
Convolved with the nonzero terms of A000217 gives the nonzero terms of A078567.

1 together with A051950.
Cf. A000005 (partial sums).
Cf. A000027, A000041, A000070, A000217, A006128, A006218, A014153, A036469, A055507, A078567, A138137, A284870, A305082, A340793.

Join[{1}, Differences[Table[DivisorSigma[0, n], {n, 1, 90}]]] (* Amiram Eldar, Feb 06 2021 *)

a(n) = A051950(n) for n > 1.

A305082 G.f.: Sum_{k>=1} x^k/(1-x^k) * Product_{k>=1} (1+x^k).

Original entry on oeis.org

0, 1, 3, 5, 9, 13, 20, 28, 39, 54, 71, 94, 124, 159, 201, 258, 322, 401, 499, 613, 750, 918, 1110, 1340, 1617, 1935, 2308, 2752, 3261, 3854, 4554, 5350, 6273, 7348, 8572, 9983, 11612, 13460, 15578, 18007, 20761, 23894, 27473, 31511, 36090, 41296, 47152, 53767

Offset: 0

Vaclav Kotesovec, May 25 2018

nonn

Convolution of A000005 and A000009.

Apart from initial zero this is the convolution of A341062 and A036469. - Omar E. Pol, Feb 16 2021

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000

Cf. A000005, A000009, A006128, A015723, A209423.

Cf. A001227, A048272, A067588, A090867, A036469, A341062.

nmax = 50; CoefficientList[Series[Sum[x^k/(1-x^k), {k, 1, nmax}]*Product[1+x^k, {k, 1, nmax}], {x, 0, nmax}], x]
nmax = 50; CoefficientList[Series[((Log[1-x] + QPolyGamma[0, 1, x]) * QPochhammer[-1, x]) / (2*Log[x]), {x, 0, nmax}], x]

a(n) ~ 3^(1/4)*(2*gamma + log(12*n/Pi^2)) * exp(Pi*sqrt(n/3)) / (4*Pi*n^(1/4)), where gamma is the Euler-Mascheroni constant A001620.

A360742 Number T(n,k) of sets of nonempty integer partitions with a total of k parts and total sum of n; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 2, 2, 0, 1, 3, 3, 2, 0, 1, 4, 6, 5, 3, 0, 1, 5, 10, 10, 7, 4, 0, 1, 6, 14, 19, 16, 10, 5, 0, 1, 7, 19, 30, 32, 24, 14, 6, 0, 1, 8, 26, 46, 57, 52, 35, 19, 8, 0, 1, 9, 32, 67, 94, 97, 79, 50, 25, 10, 0, 1, 10, 40, 93, 147, 172, 157, 117, 69, 33, 12

Offset: 0

Alois P. Heinz, Feb 18 2023

			T(6,3) = 10: {[1,1,4]}, {[1,2,3]}, {[2,2,2]}, {[1],[1,4]}, {[1],[2,3]}, {[2],[1,3]}, {[2],[2,2]}, {[3],[1,2]}, {[4],[1,1]}, {[1],[2],[3]}.
Triangle T(n,k) begins:
  1;
  0, 1;
  0, 1, 1;
  0, 1, 2,  2;
  0, 1, 3,  3,  2;
  0, 1, 4,  6,  5,  3;
  0, 1, 5, 10, 10,  7,  4;
  0, 1, 6, 14, 19, 16, 10,  5;
  0, 1, 7, 19, 30, 32, 24, 14,  6;
  0, 1, 8, 26, 46, 57, 52, 35, 19,  8;
  0, 1, 9, 32, 67, 94, 97, 79, 50, 25, 10;
  ...

Alois P. Heinz, Rows n = 0..200, flattened

Columns k=0-2 give: A000007, A057427, A001477(n-1) for n>=1.
Main diagonal gives A000009.
T(n+2,n+1) gives A036469.
Row sums give A261049.
T(2n,n) gives A360714.
Cf. A000041, A055884 (similar triangle for multisets), A330463.

h:= proc(n, i) option remember; expand(`if`(n=0, 1,
      `if`(i<1, 0, h(n, i-1)+x*h(n-i, min(n-i, i)))))
    end:
g:= proc(n, i, j) option remember; expand(`if`(j=0, 1, `if`(i<0, 0, add(
      g(n, i-1, j-k)*x^(i*k)*binomial(coeff(h(n$2), x, i), k), k=0..j))))
    end:
b:= proc(n, i) option remember; expand(`if`(n=0, 1,
     `if`(i<1, 0, add(b(n-i*j, i-1)*g(i$2, j), j=0..n/i))))
    end:
T:= (n, k)-> coeff(b(n$2), x, k):
seq(seq(T(n, k), k=0..n), n=0..12);

h[n_, i_] := h[n, i] = Expand[If[n == 0, 1, If[i < 1, 0, h[n, i - 1] + x*h[n - i, Min[n - i, i]]]]];
g[n_, i_, j_] := g[n, i, j] = Expand[If[j == 0, 1, If[i < 0, 0, Sum[       g[n, i - 1, j - k]*x^(i*k)*Binomial[Coefficient[h[n, n], x, i], k], {k, 0, j}]]]];
b[n_, i_] := b[n, i] = Expand[If[n == 0, 1, If[i < 1, 0, Sum[b[n - i*j, i - 1]*g[i, i, j], {j, 0, n/i}]]]];
T[n_, k_] := Coefficient[b[n, n], x, k];
Table[Table[T[n, k], {k, 0, n}], {n, 0, 12}] // Flatten (* Jean-François Alcover, Nov 15 2023, after Alois P. Heinz *)

T(n,n) + T(n+1,n) = T(n+2,n+1) for n>=0.

A248956 Number of polynomials a_kx^k + ... + a_1x + a_0 with k > 0, integer coefficients and only non-multiple positive integer roots and a_0 = p^n (p is a prime).

Original entry on oeis.org

1, 3, 5, 9, 13, 19, 27, 37, 49, 65, 85, 109, 139, 175, 219, 273, 337, 413, 505, 613, 741, 893, 1071, 1279, 1523, 1807, 2137, 2521, 2965, 3477, 4069, 4749, 5529, 6425, 7449, 8619, 9955, 11475, 13203, 15167, 17393, 19913, 22765, 25985, 29617, 33713, 38321, 43501

Offset: 0

Reiner Moewald, Oct 17 2014

nonn

If D_n = {p^0, ..., p^n} is the set of all positive divisors of p^n (p is a prime), then a(n) gives the number of all subsets of D_n for which the product of all their elements is a divisor of p^n. Furthermore, a(n) gives the number of all strict partitions of n including the integer 0.

			a(1) = 3: -p*x+p; -x+p; x^2 - (p+1)*x + p.

Hiroaki Yamanouchi, Table of n, a(n) for n = 0..1000

Cf. A248955, A248348.

Partial sums of A087135.

a(n) = -1 + 2*Sum_{k=0..n} a*(k) where a*(n) = A000009(n).
a(n) = A248955(p^n), where p is any prime. - Michel Marcus, Nov 07 2014
a(n) = 2*A036469(n) - 1. - Hiroaki Yamanouchi, Nov 21 2014

a(20)-a(22) from Michel Marcus, Nov 07 2014

a(23)-a(47) from Hiroaki Yamanouchi, Nov 21 2014

A277029 Convolution of A000203 and A000009.

Original entry on oeis.org

0, 1, 4, 8, 16, 25, 42, 61, 90, 130, 178, 242, 332, 436, 566, 747, 952, 1210, 1540, 1926, 2400, 2994, 3674, 4506, 5526, 6708, 8108, 9808, 11768, 14080, 16850, 20022, 23738, 28128, 33152, 39015, 45854, 53662, 62696, 73166, 85118, 98826, 114636, 132586, 153102

Offset: 0

Vaclav Kotesovec, Sep 25 2016

nonn

Apart from initial zero this is the convolution of A340793 and A036469. - Omar E. Pol, Feb 16 2021

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000

Cf. A066186 (convolution of A000203 and A000041).
Cf. A276432 (convolution of A000203 and A000219).
Cf. A066189, A036469, A340793.

Table[Sum[DivisorSigma[1, k] * PartitionsQ[n-k], {k,1,n}], {n,0,50}]
nmax = 50; CoefficientList[Series[Sum[j*x^j/(1-x^j), {j, 1, nmax}]*Product[1+x^k, {k, 1, nmax}], {x, 0, nmax}], x]

G.f.: Sum_{j>=1} (j*x^j/(1-x^j))*Product_{k>=1} (1+x^k).

a(n) ~ 2*n*A000009(n) ~ exp(Pi*sqrt(n/3)) * n^(1/4) / (2*3^(1/4)).

A277643 Partial sums of number of overpartitions (A015128).

Original entry on oeis.org

1, 3, 7, 15, 29, 53, 93, 157, 257, 411, 643, 987, 1491, 2219, 3259, 4731, 6793, 9657, 13605, 19005, 26341, 36245, 49533, 67261, 90789, 121855, 162679, 216087, 285655, 375903, 492527, 642671, 835283, 1081539, 1395347, 1793987, 2298873, 2936465, 3739401, 4747849

Offset: 0

Vaclav Kotesovec, Oct 25 2016

nonn

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000

Cf. A015128, A000070, A036469, A026906.

Cf. A211971, A002865, A087897.

Accumulate[Table[Sum[PartitionsP[n-k]*PartitionsQ[k], {k, 0, n}], {n, 0, 50}]]
nmax = 50; CoefficientList[Series[1/(1-x) * Product[(1 + x^k)/(1 - x^k), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Mar 25 2017 *)

a(n) = Sum_{k=0..n} A015128(k).
a(n) ~ exp(Pi*sqrt(n))/(4*Pi*sqrt(n)) * (1 + Pi/(4*sqrt(n))).
G.f.: 1/(1-x) * Product_{k>=1} (1 + x^k) / (1 - x^k). - Vaclav Kotesovec, Mar 25 2017
G.f.: 1/((1 - x)*theta_4(x)), where theta_4() is the Jacobi theta function. - Ilya Gutkovskiy, Apr 20 2018

A096914 Number of partitions of 2*n into distinct parts with exactly two odd parts.

Original entry on oeis.org

1, 2, 4, 7, 11, 17, 25, 36, 50, 69, 93, 124, 163, 212, 273, 349, 442, 556, 695, 863, 1066, 1310, 1602, 1950, 2364, 2854, 3433, 4115, 4916, 5854, 6951, 8229, 9716, 11442, 13441, 15752, 18419, 21490, 25021, 29074, 33718, 39031, 45101, 52024, 59910

Offset: 2

Vladeta Jovovic, Aug 18 2004

Amrik Singh Nimbran and Paul Levrie, Series of the form Sum {a_n*binomial(2n, n)}, Math. Student (2023) Vol. 92, Nos. 3-4, 155-173. See p. 9.

Cf. A000009, A036469, A015128.

Drop[ Union[ CoefficientList[ Series[x^4* Product[1 + x^(2m), {m, 1, 50}] / Product[1 - x^(2m), {m, 1, 2}], {x, 0, 920}], x]], 1] (* Robert G. Wilson v, Aug 21 2004 *)
nmax = 50; Drop[CoefficientList[Series[(x^2/(1 - x - x^2 + x^3)) * Product[1 + x^m, {m, 1, nmax}], {x, 0, nmax}], x], 2] (* Vaclav Kotesovec, May 29 2018 *)

G.f. for number of partitions of n into distinct parts with exactly k odd parts is x^(k^2)*Product(1+x^(2*m), m=1..infinity)/Product(1-x^(2*m), m=1..k).

a(n) ~ 3^(3/4) * exp(Pi*sqrt(n/3)) * n^(1/4) / (2*Pi^2). - Vaclav Kotesovec, May 29 2018

More terms from Robert G. Wilson v, Aug 21 2004

cp's OEIS Frontend

A201377 Triangle read by rows: T(n,k) (0 <= k <= n) is the number of partitions of (n,k) into a sum of distinct pairs.

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A219554 Number of bipartite partitions of (n,n) into distinct pairs.

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A026906 Number of sums S of distinct positive integers satisfying S <= n.

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A341062 Sequence whose partial sums give A000005.

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A305082 G.f.: Sum_{k>=1} x^k/(1-x^k) * Product_{k>=1} (1+x^k).

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A360742 Number T(n,k) of sets of nonempty integer partitions with a total of k parts and total sum of n; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

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A248956 Number of polynomials a_k*x^k + ... + a_1*x + a_0 with k > 0, integer coefficients and only non-multiple positive integer roots and a_0 = p^n (p is a prime).

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A277029 Convolution of A000203 and A000009.

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A248956 Number of polynomials a_kx^k + ... + a_1x + a_0 with k > 0, integer coefficients and only non-multiple positive integer roots and a_0 = p^n (p is a prime).