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 1-4 of 4 results.

A319797 Number T(n,k) of partitions of n into exactly k positive triangular numbers; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 2, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 2, 1, 1, 1, 1, 1, 0, 1, 0, 1
Offset: 0

Views

Author

Alois P. Heinz, Sep 28 2018

Keywords

Comments

Equals A181506 when the first column is removed. - Georg Fischer, Jul 26 2023

Examples

			Triangle T(n,k) begins:
  1;
  0, 1;
  0, 0, 1;
  0, 1, 0, 1;
  0, 0, 1, 0, 1;
  0, 0, 0, 1, 0, 1;
  0, 1, 1, 0, 1, 0, 1;
  0, 0, 1, 1, 0, 1, 0, 1;
  0, 0, 0, 1, 1, 0, 1, 0, 1;
  0, 0, 1, 1, 1, 1, 0, 1, 0, 1;
  0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 1;
  0, 0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 1;
  0, 0, 1, 2, 1, 1, 1, 1, 1, 0, 1, 0, 1;
		

Crossrefs

Columns k=0-10 give: A000007, A010054 (for n>0), A052344, A063993, A319814, A319815, A319816, A319817, A319818, A319819, A319820.
Row sums give A007294.
T(2n,n) gives A319799.

Programs

  • Maple
    h:= proc(n) option remember; `if`(n<1, 0,
          `if`(issqr(8*n+1), n, h(n-1)))
        end:
    b:= proc(n, i) option remember; `if`(n=0 or i=1, x^n,
          b(n, h(i-1))+expand(x*b(n-i, h(min(n-i, i)))))
        end:
    T:= n-> (p-> seq(coeff(p, x, i), i=0..n))(b(n, h(n))):
    seq(T(n), n=0..20);
  • Mathematica
    h[n_] := h[n] = If[n < 1, 0, If[IntegerQ @ Sqrt[8*n + 1], n, h[n - 1]]];
    b[n_, i_] := b[n, i] = If[n == 0 || i == 1, x^n, b[n, h[i - 1]] + Expand[ x*b[n - i, h[Min[n - i, i]]]]];
    T[n_] := Table[Coefficient[#, x, i], {i, 0, n}]& @ b[n, h[n]];
    Table[T[n], {n, 0, 20}] // Flatten (* Jean-François Alcover, May 27 2019, after Alois P. Heinz *)

Formula

T(n,k) = [x^n y^k] 1/Product_{j>=1} (1-y*x^A000217(j)).

A340953 Number of ways to write n as an ordered sum of 8 nonzero triangular numbers.

Original entry on oeis.org

1, 0, 8, 0, 28, 8, 56, 56, 70, 176, 84, 336, 196, 448, 492, 504, 953, 616, 1456, 960, 1814, 1792, 1904, 3032, 2100, 4144, 3052, 4768, 4670, 5264, 6720, 5936, 8876, 7112, 10620, 9648, 11718, 12720, 13216, 15960, 15261, 19608, 17164, 23296, 21226, 25424, 26796, 27272, 32844
Offset: 8

Views

Author

Ilya Gutkovskiy, Jan 31 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; local r, t, d; r, t, d:= $0..2;
          if n=0 then `if`(k=0, 1, 0) else
          while t<=n do r:= r+b(n-t, k-1); t, d:= t+d, d+1 od; r fi
        end:
    a:= n-> b(n, 8):
    seq(a(n), n=8..56);  # Alois P. Heinz, Jan 31 2021
  • Mathematica
    nmax = 56; CoefficientList[Series[(EllipticTheta[2, 0, Sqrt[x]]/(2 x^(1/8)) - 1)^8, {x, 0, nmax}], x] // Drop[#, 8] &

Formula

G.f.: (theta_2(sqrt(x)) / (2 * x^(1/8)) - 1)^8, where theta_2() is the Jacobi theta function.

A341025 Number of partitions of n into 8 distinct nonzero triangular numbers.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 2, 0, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0, 2, 1, 1, 2, 0, 1, 0, 2, 1, 2, 1, 0, 3, 1, 1, 3, 1, 1, 2, 1, 2, 4, 2, 2, 2, 0, 2, 5, 2, 1, 5, 2, 2, 4, 3, 4, 2, 3, 4, 3, 5, 1, 8, 4, 3, 8, 1, 4, 7, 2, 5, 7, 5, 6, 6, 4, 4, 10, 6
Offset: 120

Views

Author

Ilya Gutkovskiy, Feb 02 2021

Keywords

Crossrefs

A341791 Number of partitions of n into 8 nonzero tetrahedral numbers.

Original entry on oeis.org

1, 0, 0, 1, 0, 0, 1, 0, 0, 2, 0, 0, 2, 0, 0, 2, 0, 0, 3, 1, 0, 3, 1, 0, 3, 1, 0, 3, 2, 0, 3, 2, 0, 2, 3, 0, 3, 4, 1, 2, 4, 1, 2, 4, 1, 2, 5, 2, 2, 4, 2, 1, 5, 3, 2, 6, 4, 2, 5, 3, 2, 5, 4, 2, 6, 4, 3, 5, 5, 2, 5, 5, 4, 6, 6, 3, 6, 6, 3, 5, 6, 3, 6, 8, 4, 5, 8, 4, 5, 8, 4, 5, 10
Offset: 8

Views

Author

Ilya Gutkovskiy, Feb 19 2021

Keywords

Crossrefs

Showing 1-4 of 4 results.