A003783 -id:A003783 - cp's OEIS frontend

A055747 Expansion of Jacobi form of weight 12 and index 1 for the Niemeier lattice of type E_8^3 or D_16+E_8.

1, 0, 0, 56, 606, 0, 0, 27456, 123156, 0, 0, 3745512, 9217112, 0, 0, 95209152, 188066718, 0, 0, 1144371624, 1960489800, 0, 0, 8505838656, 13289979912, 0, 0, 45755357024, 67080028224, 0, 0, 195411318912, 272570040468, 0, 0

Offset: 0

Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Jul 11 2000

nonn

a(4*n-r^2) gives number of vectors x in the lattice of norm 2n and =r for any fixed vector in the lattice of norm 2.

M. Eichler and D. Zagier, The Theory of Jacobi Forms, Birkhauser, 1985.

Cf. A008411, A003783, A004009.

E_8*E_4, 1.

G.f.: b(z) * c(z) where b(z) is g.f. for A003783 and c(z) = 1 + 240*z^4 + 2160*z^8 + ... is A004009 expanded in powers of z^4. - Sean A. Irvine, Apr 05 2022

A115262 Correlation triangle for n+1.

Original entry on oeis.org

1, 2, 2, 3, 5, 3, 4, 8, 8, 4, 5, 11, 14, 11, 5, 6, 14, 20, 20, 14, 6, 7, 17, 26, 30, 26, 17, 7, 8, 20, 32, 40, 40, 32, 20, 8, 9, 23, 38, 50, 55, 50, 38, 23, 9, 10, 26, 44, 60, 70, 70, 60, 44, 26, 10, 11, 29, 50, 70, 85, 91, 85, 70, 50, 29, 11

Offset: 0

Paul Barry, Jan 18 2006

This sequence (formatted as a square array) gives the counts of all possible squares in an m X n rectangle. For example, 11 = 8 (1 X 1 squares) + 3 (2 X 2 square) in 4 X 2 rectangle. - Philippe Deléham, Nov 26 2009
From Clark Kimberling, Feb 07 2011: (Start)
Also the accumulation array of min{n,k}, when formatted as a rectangle.
This is the accumulation array of the array M=A003783 given by M(n,k)=min{n,k}; see A144112 for the definition of accumulation array.
The accumulation array of A115262 is A185957. (End)
From Clark Kimberling, Dec 22 2011: (Start)
As a square matrix, A115262 is the self-fusion matrix of A000027 (1,2,3,4,...).  See A193722 for the definition of fusion and A202673 for characteristic polynomials associated with A115622. (End)

			Triangle begins
  1;
  2,  2;
  3,  5,  3;
  4,  8,  8,  4;
  5, 11, 14, 11,  5;
  6, 14, 20, 20, 14,  6;
  ...
When formatted as a square matrix:
  1,  2,  3,  4,  5, ...
  2,  5,  8, 11, 14, ...
  3,  8, 14, 20, 26, ...
  4, 11, 20, 30, 40, ...
  5, 14, 26, 40, 55, ...
  ...

Cf. A000027, A202673, A271916.
For the triangular version: row sums are A001752. Diagonal sums are A097701. T(2n,n) is A000330(n+1).
Diagonals (1,5,...): A000330 (square pyramidal numbers),
diagonals (2,8,...): A007290,
diagonals (3,11,...): A051925,
diagonals (4,14,...): A159920,
antidiagonal sums: A001752.

U = NestList[Most[Prepend[#, 0]] &, #, Length[#] - 1] &[Table[k, {k, 1, 12}]];
L = Transpose[U]; M = L.U; TableForm[M]
m[i_, j_] := M[[i]][[j]];
Flatten[Table[m[i, n + 1 - i], {n, 1, 12}, {i, 1, n}]]
(* Clark Kimberling, Dec 22 2011 *)

Let f(m,n) = m*(m-1)*(3*n-m-1)/6. This array is (with a different offset) the infinite square array read by antidiagonals U(m,n) = f(n,m) if m < n, U(m,n) = f(m,n) if m <= n. See A271916. - N. J. A. Sloane, Apr 26 2016
G.f.: 1/((1-x)^2*(1-x*y)^2*(1-x^2*y)).
Number triangle T(n, k) = Sum_{j=0..n} [j<=k]*(k-j+1)[j<=n-k]*(n-k-j+1).
T(2n,n) - T(2n,n+1) = n+1.

A185957 Second accumulation array of the array min{n,k}, by antidiagonals.

Original entry on oeis.org

1, 3, 3, 6, 10, 6, 10, 21, 21, 10, 15, 36, 46, 36, 15, 21, 55, 81, 81, 55, 21, 28, 78, 126, 146, 126, 78, 28, 36, 105, 181, 231, 231, 181, 105, 36, 45, 136, 246, 336, 371, 336, 246, 136, 45, 55, 171, 321, 461, 546, 546, 461, 321, 171, 55, 66, 210, 406, 606, 756, 812, 756

Offset: 1

Clark Kimberling, Feb 07 2011

A member of the accumulation chain
... < A003982 < A003783 < A115262 < A185957 <...,
where A003783(n,k)=min{n,k}.  See A144112 for the definition of accumulation array.
A185957 also gives the symmetric matrix based on the triangular numbers s=(1,3,6,10,15,....; viz, let T be the infinite square matrix whose n-th row is formed by putting n-1 zeros before the terms of s.  Let T' be the transpose of T.  Then A185957 represents the matrix product M=T'*T.  M is the self-fusion matrix of s, as defined at A193722.  See A202678 for characteristic polynomials of principal submatrices of M.

			Northwest corner:
1....3....6....10...15
3....10...21...36...55
6....21...46...81...126
10...36...81...146..231

G. C. Greubel, Table of n, a(n) for the first 50 rows, flattened

Cf. A144112, A003783, A115262.

U = NestList[Most[Prepend[#, 0]] &, #, Length[#] - 1] &[Table[k (k + 1)/2, {k, 1, 15}]];
L = Transpose[U]; M = L.U; TableForm[M]
m[i_, j_] := M[[i]][[j]];
Flatten[Table[m[i, n + 1 - i], {n, 1, 12}, {i, 1, n}]]
f[n_] := Sum[m[i, n], {i, 1, n}] + Sum[m[n, j], {j, 1, n - 1}]
Table[f[n], {n, 1, 12}]
Table[Sqrt[f[n]], {n, 1, 12}] (* A000292 *)
Table[m[1, j], {j, 1, 12}] (* A000217 *)
Table[m[2, j], {j, 1, 12}] (* A014105 *)
Table[m[j, j], {j, 1, 12}] (* A024166 *)
Table[m[j, j + 1], {j, 1, 12}] (* A112851 *)
Table[Sum[m[i, n + 1 - i], {i, 1, n}], {n, 1, 12}] (* A001769 *)

A003982 Table read by rows: 1 if x = y, 0 otherwise, where (x,y) = (0,0),(0,1),(1,0),(0,2),(1,1),(2,0),...

Original entry on oeis.org

1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset: 0

Marc LeBrun

Also called the delta function.
From Clark Kimberling, Feb 07 2011: (Start)
In rectangular format, the infinite identity matrix and the weight array of A003783(n,k)=min{n,k}; in the accumulation chain
... < A003982 < A003783 < A115262 < A185957 < ... . See A144112 for definitions of weight array and accumulation array. (End)

			Table begins
  1;
  0, 0;
  0, 1, 0;
  0, 0, 0, 0;
  0, 0, 1, 0, 0;
  ....
Northwest corner when formatted as a rectangular array:
  1 0 0 0 0 0 0 0
  0 1 0 0 0 0 0 0
  0 0 1 0 0 0 0 0
  0 0 0 1 0 0 0 0
  0 0 0 0 1 0 0 0

Antti Karttunen, Table of n, a(n) for n = 0..65537
Index entries for characteristic functions

Characteristic function of A001844. Antidiagonal sums and main diagonal is A000012.

Cf. also A286100.

f[n_,k_]:=0; f[n_,n_]:=1;
TableForm[Table[f[n,k],{n,1,10},{k,1,10}]] (* array *)
Table[f[n-k+1,k],{n,10},{k,n,1,-1}]//Flatten (*sequence *)
Table[Join[{1},Table[0,4n-1]],{n,10}]//Flatten (* Harvey P. Dale, Dec 21 2016 *)

{a(n) = issquare(2*n + 1)}; /* Michael Somos, Apr 13 2005 */

{a(n) = local(A); if( n<0, 0, A = x * O(x^n); polcoeff( eta(x^8 + A)^2 / eta(x^4 + A), n))};

PARI
```
A(i,j)=i==j
```

n-th 1 is followed by 4*n-1 0's. In the sequence with flattened indices, the 1's are at positions listed in A046092.
G.f.: 1/(1 - x*y). E.g.f.: exp(x*y).
Considered as a linear sequence, expansion of q^(-1/2)*eta(q^8)^2/eta(q^4) in powers of q. If A(x) is the g.f., then B(a) = (q*A(a^2))^2 satisfies 0 = f(B(q), B(q^2), B(q^4)) where f(u, v, w) = u^2*w - v^3 - 4*v*w^2. Also, given g.f. A(x), then B(q) = q*A(q^2) satisfies 0 = f(B(q), B(q^2), B(q^3), B(q^6)) where f(u1, u2, u3, u6) = u1*u2^2*u6 - u1*u6^3 - u3^3*u2. - Michael Somos, Apr 13 2005
a(n) = b(2*n + 1) where b(n) is multiplicative and b(2^e) = 0^e, b(p^e) = (1 + (-1)^e)/2 if p>2. - Michael Somos, Jun 06 2005
a(n) = floor(sqrt(2*n+1)) - floor(sqrt(2*n)). - Ridouane Oudra, Oct 09 2020

A003782 Coefficients of Jacobi Eisenstein series of index 1 and weight 6.

Original entry on oeis.org

1, 0, 0, -88, -330, 0, 0, -4224, -7524, 0, 0, -30600, -46552, 0, 0, -130944, -169290, 0, 0, -355080, -464904, 0, 0, -899712, -1052040, 0, 0, -1732192, -2099328, 0, 0, -3421440, -3859812, 0, 0, -5593104

Offset: 0

N. J. A. Sloane

sign

M. Eichler and D. Zagier, The Theory of Jacobi Forms, Birkhauser, 1985, p. 141.

Cf. A003783.

t3^3*(t3^8-11*(t3^4*t2^4)/8+11*(t2^8)/32) where tj=theta_j(z) is associated weight 11/2 form. - Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), May 26 2000

cp's OEIS Frontend

A055747 Expansion of Jacobi form of weight 12 and index 1 for the Niemeier lattice of type E_8^3 or D_16+E_8.

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A115262 Correlation triangle for n+1.

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A185957 Second accumulation array of the array min{n,k}, by antidiagonals.

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A003982 Table read by rows: 1 if x = y, 0 otherwise, where (x,y) = (0,0),(0,1),(1,0),(0,2),(1,1),(2,0),...

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A003782 Coefficients of Jacobi Eisenstein series of index 1 and weight 6.

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