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.

A346049 a(0) = ... = a(4) = 1; a(n) = Sum_{k=1..n-5} a(k) * a(n-k-5).

Original entry on oeis.org

1, 1, 1, 1, 1, 0, 1, 2, 3, 4, 4, 4, 6, 10, 16, 24, 30, 37, 50, 74, 116, 175, 245, 332, 456, 654, 981, 1471, 2146, 3056, 4320, 6203, 9119, 13540, 19986, 29134, 42113, 61047, 89398, 132021, 195272, 287547, 421235, 616418, 905161, 1335648, 1976407, 2922982, 4313230
Offset: 0

Views

Author

Ilya Gutkovskiy, Jul 02 2021

Keywords

Crossrefs

Programs

  • Mathematica
    a[0] = a[1] = a[2] = a[3] = a[4] = 1; a[n_] := a[n] = Sum[a[k] a[n - k - 5], {k, 1, n - 5}]; Table[a[n], {n, 0, 48}]
    nmax = 48; A[] = 0; Do[A[x] = 1 + x + x^2 + x^3 + x^4 + x^5 A[x] (A[x] - 1) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
  • SageMath
    @CachedFunction
    def a(n): # a = A346049
        if (n<5): return 1
        else: return sum(a(k)*a(n-k-5) for k in range(1,n-4))
    [a(n) for n in range(51)] # G. C. Greubel, Nov 28 2022

Formula

G.f. A(x) satisfies: A(x) = 1 + x + x^2 + x^3 + x^4 + x^5 * A(x) * (A(x) - 1).

A346048 a(0) = ... = a(3) = 1; a(n) = Sum_{k=1..n-4} a(k) * a(n-k-4).

Original entry on oeis.org

1, 1, 1, 1, 0, 1, 2, 3, 3, 3, 5, 9, 15, 19, 24, 35, 59, 95, 137, 191, 280, 445, 706, 1071, 1575, 2357, 3663, 5755, 8890, 13483, 20518, 31759, 49658, 77267, 119135, 183523, 284793, 444883, 694798, 1080865, 1679142, 2616399, 4092497, 6408249, 10021176, 15657643
Offset: 0

Views

Author

Ilya Gutkovskiy, Jul 02 2021

Keywords

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; `if`(n<4, 1,
          add(a(j)*a(n-4-j), j=1..n-4))
        end:
    seq(a(n), n=0..45);  # Alois P. Heinz, Jul 03 2021
  • Mathematica
    a[0] = a[1] = a[2] = a[3] = 1; a[n_] := a[n] = Sum[a[k] a[n - k - 4], {k, 1, n - 4}]; Table[a[n], {n, 0, 45}]
    nmax = 45; A[] = 0; Do[A[x] = 1 + x + x^2 + x^3 + x^4 A[x] (A[x] - 1) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]

Formula

G.f. A(x) satisfies: A(x) = 1 + x + x^2 + x^3 + x^4 * A(x) * (A(x) - 1).

A346075 a(n) = 1 + Sum_{k=1..n-3} a(k) * a(n-k-3).

Original entry on oeis.org

1, 1, 1, 1, 2, 3, 4, 6, 10, 16, 25, 41, 69, 115, 192, 326, 558, 955, 1641, 2839, 4930, 8578, 14972, 26222, 46037, 80988, 142793, 252307, 446617, 791885, 1406394, 2501642, 4456080, 7947963, 14194221, 25379751, 45430710, 81409233, 146028788, 262192876, 471193406
Offset: 0

Views

Author

Ilya Gutkovskiy, Jul 04 2021

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := a[n] = 1 + Sum[a[k] a[n - k - 3], {k, 1, n - 3}]; Table[a[n], {n, 0, 40}]
    nmax = 40; A[] = 0; Do[A[x] = 1/(1 - x) + x^3 A[x] (A[x] - 1) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
  • SageMath
    @CachedFunction
    def a(n): # a = A346075
        if (n<4): return 1
        else: return 1 + sum(a(k)*a(n-k-3) for k in range(1,n-2))
    [a(n) for n in range(51)] # G. C. Greubel, Nov 27 2022

Formula

G.f. A(x) satisfies: A(x) = 1 / (1 - x) + x^3 * A(x) * (A(x) - 1).
Showing 1-3 of 3 results.