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 11-15 of 15 results.

A308684 Partition array T(n, k) for the coefficients of the n-th power sums of the second elementary symmetric function in terms of the elementary symmetric functions.

Original entry on oeis.org

1, 2, -2, 1, 3, -3, -3, 3, 3, -3, 1, 4, -4, -4, -4, 6, 4, 8, -8, -4, 4, -4, 4, 2, -4, 1, 5, -5, -5, -5, -5, 10, 5, 10, 10, -15, 5, -15, 5, 5, -5, -15, 10, 5, 10, -5, -5, -5, 5, 5, 5, -5, 5, 5, -5, 1
Offset: 1

Views

Author

Wolfdieter Lang, Jul 08 2019

Keywords

Comments

The length of row n is A209816(n) (number of partitions of 2*n with at most n parts).
This is a generalization of the Girard-Waring array A115131.
In A324254 the general definition psigma(n, r) has been given for the r-th power sum of the n-th elementary symmetric function. There it is given in terms of the ordinary power sums {ps(j*r)}_{j=1..n}. Here psigma(2, n) = (1/2)*(-ps(2*n) + (ps(n))^2) is considered (see row n = 2 in A324254), and it is written in terms of elementary symmetric functions e_k(x1, x2, ...x_N), using the Girard-Waring formula for power sums ps. The number N >= 1 of indeterminates is suppressed in the notations.

Examples

			The irregular triangle (partition array) T(n, k)  begins:
n\k 1  2  3  4  5   6  7  8   9  10  11  12 13 14 15 ...
-------------------------------------------------------------------------------------------
1:  1
2:  2 -2  1
3:  3 -3 -3  3  3  -3  1
4:  4 -4 -4 -4  6   4  8 -8  -4   4  -4   4  2 -4  1
...
n = 5: [[5], [-5, -5, -5, -5, 10], [5, 10, 10, -15, 5, -15, 5, 5], [-5, -15, 10, 5, 10, -5, -5, -5, 5], [5, 5, -5, 5, 5, -5, 1]];
n = 6: [[6],[-6, -6, -6, -6, -6, 15], [6, 12, 12, 12, -24, 6, 12. -24, 6, -12, 12, 2], [-6, -18, -18, 18, 9, -18, 36, 0, 0, -18, 6, -18, 9, 0, 3], [6, 24, -12, -12, -18, 0, 0, 18, 12, 0, -12, -6, 6], [-6, 6, 6, 3,-6,-12, -2, 6, 9, -6, 1]];
n = 7: [[7], [-7, -7, -7, -7, -7, -7, 21] , [7, 14, 14, 14, 14, -35, 7, 14, 14, -35, 7, 7, -35, 14, 7, 7], [-7, -21, -21, -21, 28, 14, -21,-42, 56, 7, 28, 7, -21, -21, -7, 28, -21, 14, -21, 7, -7, -7, 14],  [7, 28, 28, -21, -21, 42, -63, -14, -7, -7, 35, 14, -21, 35, -14, 35, -14, -21, 7, -21, 14, -7, 7], [-7, -35, 14, 14, 7, 28, 7, 7, -21, -21,-21,-14, -7, 35, 7, 14, 7, -21, -7, 7], [7, -7, -7, -7, 7, 14, 7, 7, -7, -21, -7, 7, 14, -7, 1]]:
Brackets combine terms belonging to the same number of parts.
...
n = 3: psigma(2, 3) := Sum_{1<= i1 < i2 <= N} (x_{i1}*x_{i2})^3 = (1/2)*(-ps(2*3) + (ps(3))^2) = 3*e_6 - 3*e_1*e_5 - 3*e_2*e_4 + 3*(e_3)^2 + 3*(e_1)^2*e_4 - 3*e_1*e_2*e_3 + (e_2)^3. This becomes an identity if the e_j are written in terms of the indeterminates x_1, ..., x_N, for any N >= 1.
		

Crossrefs

Cf. A115121, A324254 (psigma(2, n) in terms of power sums).

Formula

psigma(2, n) = Sum_{k=1.. A209816(n)} T(n, k)*Product_{j=1..2*n} (e_j)^a(2*n,k,j), for n >= 1, if the k-th partition of 2*n (in Abramowitz-Stegun order) is Product_{j=1..2*n} j^a(2*n,k,j). Here the elemntary symmetric functions are e_j = e_j^{(N)} for N indeterminates x_1, ..., x_N, for any N >= 1.

A324247 Partition array giving in row n, for n >= 1, the coefficients of the Witt symmetric function w_n in terms of the elementary symmetric functions (using partitions in the Abramowitz-Stegun order).

Original entry on oeis.org

1, -1, 0, 1, -1, 0, -1, 1, 0, -1, 0, 1, -1, -1, 1, 1, -1, 0, -1, 1, 1, 0, -1, -1, 0, 1, 1, -1, 0, 1, -1, -1, -1, 1, 2, 1, 1, -1, -3, -1, 1, 2, -1, 0, -1, 1, 1, 1, 0, -1, -2, -1, -1, -1, 1, 2, -2, 3, 0, -1, -3, 0, 1, 2, -1, 0, 1, -1, -1, -1, -1, 1, 2, 2, 1, 1, 2, 0, -1, -3, -3, -3, -2, -1, 1, 4, 2, 5, 1, -1, -5, -3, 1, 3, -1, 0, -1, 1, 1, 1, 1, 0, -1, -2, -2, -1, -1, -1, -1, -1, 1, 3, 2, 1, 2, 5, 1, 1, 1, -1, -3, -3, -5, -5, -3, 0, 1, 4, 2, 8, 2, -1, -5, -4, 1, 3, -1, 0
Offset: 1

Views

Author

Wolfdieter Lang, May 23 2019

Keywords

Comments

The length of row n is A000041(n).
The (one part) Witt symmetric function w_n is defined in the links below (one can add w_0 = 1). It can be expressed in terms of the elementary symmetric functions {e_i}{i=1..n} by using first a recurrence to express w_n in terms of the power sum symmetric functions p_n = Sum{1>=1} x_i^n, for the indeterminates {x_i}, by w_n = (1/n)*(p_n - Sum_{d|n, 1 <= d < n} d*(w_d)^{n/d}), n >= 2, with w_1 = p_1 = e_1. (See the array A324253). The p_n can then be expressed in terms of {e_i}_{i=1..n} by the Newton recurrence or its solution, the Girard-Waring formula (see A115131, row n, with partitions in the Abramowitz-Stegun order).
A relation between {w_n}{n>=1}, {e_i}{i>=0}, with e_0 = 1, and the indeterminates {x_i}{i>=1} is: Product{n>=0}(1 - w_n*t^n) = Sum_{i>=0} e_i*(-t)^i = Product_{j>=1} (1 - x_j*t). See the links.
If only N indeterminates {x_i}_{i=1..N} are considered all coefficients corresponding to partitions with at least one part > N are set to 0 (in addition to the ones given in the sequence).

Examples

			The irregular triangle (partition array) begins:
n\k  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 ...
------------------------------------------------------------------------------
1:   1
2:  -1  0
3:   1 -1  0
4:  -1  1  0 -1  0
5:   1 -1 -1  1  1 -1  0
6:  -1  1  1  0 -1 -1  0  1  1 -1  0
7:   1 -1 -1 -1  1  2  1  1 -1 -3 -1  1  2 -1  0
8:  -1  1  1  1  0 -1 -2 -1 -1 -1  1  2 -2  3  0 -1 -3  0  1  2 -1  0
...
n = 9: 1 -1 -1 -1 -1 1 2 2 1 1 2 0 -1 -3 -3 -3 -2 -1 1 4 2 5 1 -1 -5 -3 1 3 -1 0;
n = 10: -1 1 1 1 1 0 -1 -2 -2 -1 -1 -1 -1 -1 1 3 2 1 2 5 1 1 1 -1 -3 -3 -5 -5 -3 0 1 4 2 8 2 -1 -5 -4 1 3 -1 0;
...
---------------------------------------------------------------------------------
w_1 = e_1;
w_2 = - e_2 + 0;
w_3 = e_3 - e_1*e_2 + 0;
w_4:= - e_4 + e_1*e_3 + 0 - (e_1)^2*e_2 + 0;
w_5 = e_5 - e_1*e_4 - e_2*e_3 + (e_1)^2*e_3 + e_1*(e_2)^2 - (e_1)^3*e_2 + 0;
w_6 = - e_6 + e_1*e_5 + e_2*e_4 + 0 - (e_1)^2*e_4 - e_1*e_2*e_3 + 0 + (e_1)^3*e_3 + (e_1)^2*(e_2)^2 - (e_1)^4*e_2 + 0;
...
---------------------------------------------------------------------------------
		

Crossrefs

Cf. A000041, A115131 (Waring numbers), A324253 (with power sums).

Formula

w_n is given by the recurrence given in the comment above via the power sum symmetric functions {p_i} expressed in terms of the elementary symmetric functions {e_i}.
T(n, k) gives the coefficient of (e_1)^{a(k,1)}* ... *(e_n)^{a(k,n)} for w_n, corresponding to the k-th partition of n in Abramowitz-Stegun order, written as 1^{a(k,1)}* ... *n^{a(k,n)}, with nonnegative integers a(k,j) satisfying Sum_{j=1..n} j*a(k,j) = n, and the number of parts is Sum_{j=1..n} a(k,j) =: m.

A324253 Partition array giving in row n, for n >= 1, the coefficients of the Witt symmetric function w_n, multiplied by n!, in terms of the power sum symmetric functions (using partitions in the Abramowitz-Stegun order).

Original entry on oeis.org

1, 1, -1, -2, 0, -2, 6, 0, -3, 6, -9, 24, 0, 0, 0, 0, 0, -24, 120, 0, 0, -40, 0, 0, -30, 80, 90, -90, -130, 720, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -720, 5040, 0, 0, 0, -1260, 0, 0, 0, 1260, 0, 0, 2520, 3780, 0, -945, 3780, 0, 0, 0, -6930, 6300, -8505
Offset: 1

Views

Author

Wolfdieter Lang, Jun 05 2019

Keywords

Comments

The length of row n is A000041(n).
The (one part) Witt symmetric function w_n is defined in the links below. One should add w_0 = 1. It can be expressed in terms of the power sum symmetric functions p_k = Sum_{i>=1} (x_i)^k for the indeterminates {x_i}, by using the recurrence w_n = (1/n)*(p_n - Sum_{d|n,1 <= d < n} d*(w_d)^{n/d}), n >= 2, with w_1 = p_1.
In order to have integer coefficients n!*w_n is considered, and terms are listed in the Abramowitz-Stegun order (with rising number of parts).
A logarithmic generating function of the power sums is related to the {w_n}{n>=1} sequence by Lp(t) := -Sum{j>=1} p_j*(t^j)/j = log(Product_{n>=0} (1 - w_n*t^n)). See the links.
If only N indeterminates {x_i}_{i=1..N} are considered all coefficients corresponding to partitions with at least one part > N are set to 0 (in addition to the ones given in the sequence).

Examples

			The irregular triangle (partition array) begins:
n\k    1  2  3   4  5  6   7   8   9  10   11 12 13 14  15  ...
---------------------------------------------------------------
1:     1
2:     1 -1
3:    -2  0 -2
4:     6  0 -3   6 -9
5:    24  0  0   0  0  0 -24
6:   120  0  0 -40  0  0 -30  80  90 -90 -130
7:   720  0  0   0  0  0   0   0   0   0    0  0  0  0 -720
...
n = 8:  5040 0 0 0 -1260 0 0 0 1260 0 0 2520 3780 0 -945 3780 0 0 0 -6930 6300 -8505;
n = 9: 40320 0 0 0 0 0 0 0 0 0 0 -4480 0 0 0 0 0 0 0 0 13440 0 0 0 0 0 -13440 0 0 -35840;
n = 10: 362880 0 0 0 0 -725760 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -22680 145152 0 0 0 113400 0 0 -226800 0 226800 -113400 -412776;
...
---------------------------------------------------------------
w_1 = p_1;
w_2 = (1/2)*(p_2 - (p_1)^2);
w_3 = (1/3!)*(2*p_3 + 0 - 2*(p_1)^3);
w_4 = (1/4!)*(6*p_4 + 0 - 3*(p_2)^2 + 6*(p_1)^2*p_2 - 9*(p_1)^4);
w_5 = (1/5!)*(24*p_5 + 0 + 0 + 0 + 0 + 0 - 24*(p_1)^5) = (1/5)*(p_5 - (p_1)^5);
w_6 = (1/6!)*(120*p_6 + 0 + 0 - 40*(p_3)^2 + 0 + 0 - 30*(p_2)^3 + 80*(p_1)^3*p_3 + 90*(p_1)^2*(p_2)^2 - 90*(p_1)^4*p_2 - 130*(p_1)^6)
  = (1/72)*(12*p_6 - 4*(p_3)^2 - 3*(p_2)^3 + 8*(p_1)^3*p_3 + 9*(p_1)^2*(p_2)^2 -   9*(p_1)^4*p_2 - 13*(p_1)^6);
...
---------------------------------------------------------------
		

Crossrefs

Cf. A000041, A115131 (Waring numbers), A324247.

Formula

w_n is given by the recurrence given in the comment above in terms of the power sum symmetric functions {p_i}_{i>=1}, for n >= 1.
T(n, k) gives the coefficient of (p_1)^{a(1,k)}*...*(p_n)^{a(n,k)} for n!*w_n, corresponding to the k-th partition of n in Abramowitz-Stegun order, written as 1^{a(1,k)}*...*n^{a(n,k)}, with nonnegative integers a(n,j) satisfying Sum_{j=1..n} j*a(n,j) = n. The number of parts is Sum_{j=1..n} a(n,k) =: m(k).

A330415 Coefficient of h(y) in Sum_{k > 0, i > 0} x_i^k = p(1) + p(2) + p(3) + ..., where h is the basis of homogeneous symmetric functions, p is the basis of power-sum symmetric functions, and y is the integer partition with Heinz number n.

Original entry on oeis.org

0, 1, 2, -1, 3, -3, 4, 1, -2, -4, 5, 4, 6, -5, -5, -1, 7, 5, 8, 5, -6, -6, 9, -5, -3, -7, 2, 6, 10, 12, 11, 1, -7, -8, -7, -9, 12, -9, -8, -6, 13, 14, 14, 7, 7, -10, 15, 6, -4, 7, -9, 8, 16, -7, -8, -7, -10, -11, 17, -21, 18, -12, 8, -1, -9, 16, 19, 9, -11, 16
Offset: 1

Views

Author

Gus Wiseman, Dec 14 2019

Keywords

Comments

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).
Up to sign, a(n) is the number of acyclic spanning subgraphs of an undirected n-cycle whose component sizes are the prime indices of n.

Crossrefs

The unsigned version (except with a(1) = 1) is A319225.
The transition from p to e by Heinz numbers is A321752.
The transition from p to h by Heinz numbers is A321754.
Different orderings with and without signs and first terms are A115131, A210258, A263916, A319226, A330417.

Programs

  • Mathematica
    Table[If[n==1,0,(-1)^(PrimeOmega[n]-1)*Total[Cases[FactorInteger[n],{p_,k_}:>k*PrimePi[p]]]*(PrimeOmega[n]-1)!/(Times@@Factorial/@FactorInteger[n][[All,2]])],{n,30}]

Formula

a(n) = (-1)^(Omega(n) - 1) * A056239(n) * (Omega(n) - 1)! / Product c_i! where c_i is the multiplicity of prime(i) in the prime factorization of n.

A330417 Coefficient of e(y) in Sum_{k > 0, i > 0} x_i^k = p(1) + p(2) + p(3) + ..., where e is the basis of elementary symmetric functions, p is the basis of power-sum symmetric functions, and y is the integer partition with Heinz number n.

Original entry on oeis.org

0, 1, -2, 1, 3, -3, -4, 1, 2, 4, 5, -4, -6, -5, -5, 1, 7, 5, -8, 5, 6, 6, 9, -5, 3, -7, -2, -6, -10, -12, 11, 1, -7, 8, -7, 9, -12, -9, 8, 6, 13, 14, -14, 7, 7, 10, 15, -6, 4, 7, -9, -8, -16, -7, 8, -7, 10, -11, 17, -21, -18, 12, -8, 1, -9, -16, 19, 9, -11
Offset: 1

Views

Author

Gus Wiseman, Dec 14 2019

Keywords

Comments

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).
Up to sign, a(n) is the number of acyclic spanning subgraphs of an undirected n-cycle whose component sizes are the prime indices of n.

Crossrefs

The unsigned version (except with a(1) = 1) is A319225.
The transition from p to e by Heinz numbers is A321752.
The transition from p to h by Heinz numbers is A321754.
Different orderings with and without signs and first terms are A115131, A210258, A263916, A319226, A330415.

Programs

  • Mathematica
    Table[If[n==1,0,With[{tot=Total[Cases[FactorInteger[n],{p_,k_}:>k*PrimePi[p]]]},(-1)^(tot-PrimeOmega[n])*tot*(PrimeOmega[n]-1)!/(Times@@Factorial/@FactorInteger[n][[All,2]])]],{n,30}]

Formula

a(n) = (-1)^(A056239(n) - Omega(n)) * A056239(n) * (Omega(n) - 1)! / Product c_i! where c_i is the multiplicity of prime(i) in the prime factorization of n.
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