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 1-3 of 3 results.

A319394 Number T(n,k) of partitions of n into exactly k positive Fibonacci numbers; 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, 1, 1, 0, 0, 2, 1, 1, 0, 1, 1, 2, 1, 1, 0, 0, 2, 2, 2, 1, 1, 0, 0, 1, 3, 2, 2, 1, 1, 0, 1, 1, 2, 4, 2, 2, 1, 1, 0, 0, 1, 3, 3, 4, 2, 2, 1, 1, 0, 0, 2, 2, 4, 4, 4, 2, 2, 1, 1, 0, 0, 1, 3, 4, 5, 4, 4, 2, 2, 1, 1, 0, 0, 0, 3, 5, 5, 6, 4, 4, 2, 2, 1, 1
Offset: 0

Views

Author

Alois P. Heinz, Sep 18 2018

Keywords

Comments

T(n,k) is defined for n,k >= 0. The triangle contains only the terms with k <= n. T(n,k) = 0 for k > n.

Examples

			T(14,3) = 2: 851, 833.
T(14,4) = 5: 8321, 8222, 5531, 5522, 5333.
T(14,5) = 6: 83111, 82211, 55211, 53321, 53222, 33332.
T(14,6) = 8: 821111, 551111, 533111, 532211, 522221, 333311, 333221, 332222.
T(14,7) = 7: 8111111, 5321111, 5222111, 3332111, 3322211, 3222221, 2222222.
T(14,8) = 6: 53111111, 52211111, 33311111, 33221111, 32222111, 22222211.
Triangle T(n,k) begins:
  1;
  0, 1;
  0, 1, 1;
  0, 1, 1, 1;
  0, 0, 2, 1, 1;
  0, 1, 1, 2, 1, 1;
  0, 0, 2, 2, 2, 1, 1;
  0, 0, 1, 3, 2, 2, 1, 1;
  0, 1, 1, 2, 4, 2, 2, 1, 1;
  0, 0, 1, 3, 3, 4, 2, 2, 1, 1;
  0, 0, 2, 2, 4, 4, 4, 2, 2, 1, 1;
  0, 0, 1, 3, 4, 5, 4, 4, 2, 2, 1, 1;
  0, 0, 0, 3, 5, 5, 6, 4, 4, 2, 2, 1, 1;
  0, 1, 1, 2, 4, 7, 6, 6, 4, 4, 2, 2, 1, 1;
  0, 0, 1, 2, 5, 6, 8, 7, 6, 4, 4, 2, 2, 1, 1;
  ...
		

Crossrefs

Columns k=0-10 give: A000007, A010056 (for n>0), A319395, A319396, A319397, A319398, A319399, A319400, A319401, A319402, A319403.
Row sums give A003107.
T(2n,n) gives A136343.

Programs

  • Maple
    h:= proc(n) option remember; `if`(n<1, 0, `if`((t->
          issqr(t+4) or issqr(t-4))(5*n^2), 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
    T[n_, k_] := SeriesCoefficient[1/Product[(1 - y x^Fibonacci[j]) + O[x]^(n+1) // Normal, {j, 2, n+1}], {x, 0, n}, {y, 0, k}];
    Table[T[n, k], {n, 0, 40}, {k, 0, n}] // Flatten (* Jean-François Alcover, May 28 2020 *)
    h[n_] := h[n] = If[n < 1, 0, If[Function[t, IntegerQ@Sqrt[t + 4] || IntegerQ@Sqrt[t - 4]][5 n^2], n, h[n - 1]]];
    b[n_, i_, t_] := b[n, i, t] = If[n == 0, 1, If[i < 1 || t < 1, 0, b[n, h[i - 1], t] + b[n - i, h[Min[n - i, i]], t - 1]]];
    T[n_, k_] :=  b[n, h[n], k] - b[n, h[n], k - 1];
    Table[T[n, k], {n, 0, 20}, {k, 0, n}] // Flatten (* Jean-François Alcover, Dec 07 2020, after Alois P. Heinz *)

Formula

T(n,k) = [x^n y^k] 1/Product_{j>=2} (1-y*x^A000045(j)).
Sum_{k=1..n} k * T(n,k) = A281689(n).
T(A000045(n),n) = A319503(n).

A357690 Number of ways to write n as an ordered sum of five positive Fibonacci numbers (with a single type of 1).

Original entry on oeis.org

1, 5, 15, 30, 50, 71, 95, 115, 140, 165, 191, 205, 220, 240, 260, 285, 310, 325, 325, 320, 341, 350, 380, 385, 405, 420, 430, 450, 465, 465, 445, 410, 435, 425, 450, 481, 495, 515, 490, 510, 555, 525, 580, 540, 530, 570, 530, 580, 600, 520, 525, 440, 455, 520, 445, 555, 530
Offset: 5

Views

Author

Ilya Gutkovskiy, Oct 10 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 61; CoefficientList[Series[Sum[x^Fibonacci[k], {k, 2, 21}]^5, {x, 0, nmax}], x] // Drop[#, 5] &

Formula

G.f.: ( Sum_{k>=2} x^Fibonacci(k) )^5.
a(n) = A121548(n,5).

A358005 Number of partitions of n into 5 distinct positive Fibonacci numbers (with a single type of 1).

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 1, 0, 0, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 3, 2, 2, 2, 1, 2, 2, 2, 2, 1, 2, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 2, 2, 2, 3, 1, 2, 2, 1, 3, 2, 2, 2, 1, 2
Offset: 19

Views

Author

Ilya Gutkovskiy, Oct 24 2022

Keywords

Crossrefs

Programs

  • Maple
    G:= mul(1+t*x^combinat:-fibonacci(k),k=2..21):
    S:= coeff(expand(G),t,5):
    seq(coeff(S,x,i),i=19..110); # Robert Israel, Jan 06 2023
Showing 1-3 of 3 results.