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.

A341240 a(n) = 4*a(n-1) - 2*a(n-2) + a(n-3) - 4*a(n-4) + 2*a(n-5) for n >= 7, where a(1) = 1, a(2) = 2, a(3) = 4, a(4) = 12, a(5) = 38, a(6) = 127.

Original entry on oeis.org

1, 2, 4, 12, 38, 127, 432, 1472, 5023, 17148, 58544, 199879, 682428, 2329952, 7954951, 27159900, 92729696, 316598983, 1080936540, 3690548192, 12600319687, 43020182364, 146880090080, 501479995591, 1712159802204, 5845679217632, 19958397266119, 68142230629212
Offset: 1

Views

Author

Clark Kimberling, Feb 07 2021

Keywords

Crossrefs

Programs

  • Mathematica
    z = 50; r = 1 + Sqrt[2]; s = Sqrt[2]; f[x_] := Floor[r*Floor[s*x]];
    Table[f[n], {n, 1, z}] (* A341239 *)
    a[1] = 1; a[n_] := f[a[n - 1]];
    Table[a[n], {n, 1, z}] (* A341240 *)
    LinearRecurrence[{4,-2,1,-4,2},{1,2,4,12,38,127},30] (* Harvey P. Dale, Jun 14 2022 *)

Formula

Let f(n) = floor(r*floor(s*n)) = A184922(n), where r = 1 + sqrt(2) and s = sqrt(2). Let a(1) = 1. Then a(n) = f(a(n-1)) for n >= 2.
G.f.: x*(1 - 2*x - 2*x^2 - x^3 + x^5)/(1 - 4*x + 2*x^2 - x^3 + 4*x^4 - 2*x^5). - Stefano Spezia, Feb 11 2021

A341250 a(n) = 5*a(n-1) - 4*a(n-3) for n >= 4, where a(1) = 1, a(2) = 3, a(3) = 13.

Original entry on oeis.org

1, 3, 13, 61, 293, 1413, 6821, 32933, 159013, 767781, 3707173, 17899813, 86427941, 417311013, 2014955813, 9729067301, 46976092453, 226820639013, 1095186925861, 5288030259493, 25532868741413, 123283596003621, 595265858980133, 2874197819935013
Offset: 1

Views

Author

Clark Kimberling, Feb 13 2021

Keywords

Crossrefs

Programs

  • Mathematica
    z = 40; r = 2 + Sqrt[2]; s = Sqrt[2]; f[x_] := Floor[r*Floor[s*x]];
    Table[f[n], {n, 1, z}] (* A341249 *)
    a[1] = 1; a[n_] := f[a[n - 1]];
    Table[a[n], {n, 1, z}] (* A341250 *)

Formula

Let f(n) = floor(r*floor(s*n)) = A341249(n), where r = 2 + sqrt(2) and s = sqrt(2). Let a(1) = 1. Then a(n) = f(a(n-1)) for n >= 2.
a(n) = (A218989(n-2) + 1)/2. - Hugo Pfoertner, Feb 13 2021
G.f.: x*(-2*x^2 - 2*x + 1)/(4*x^3 - 5*x + 1). - Chai Wah Wu, Feb 15 2021

A341255 Let f(n) = floor(r*floor(r*n)) = A341254(n), where r = (2 + sqrt(5))/2. Let a(1) = 1. Then a(n) = f(a(n-1)) for n >= 2.

Original entry on oeis.org

1, 4, 16, 69, 309, 1385, 6212, 27866, 125008, 560793, 2515754, 11285842, 50629052, 227125366, 1018899829, 4570853893, 20505161277, 91987547377, 412662390616, 1851231536059, 8304750512850, 37255675336820, 167131492108634, 749763234780300, 3363488838254558
Offset: 1

Views

Author

Clark Kimberling, Feb 13 2021

Keywords

Crossrefs

Programs

  • Mathematica
    z = 40; u = GoldenRatio;
    r = u + 1/2; f[x_] := Floor[r*Floor[r*x]];
    Table[f[n], {n, 1, z}]  (* A341254 *)
    a[1] = 1; a[n_] := f[a[n - 1]];
    Table[a[n], {n, 1, z}]  (* A341255 *)

A341248 a(n) = 5*a(n-1) - 4*a(n-3) for n >= 4, where a(1) = 1, a(2) = 4, a(3) = 18.

Original entry on oeis.org

1, 4, 18, 86, 414, 1998, 9646, 46574, 224878, 1085806, 5242734, 25314158, 122227566, 590166894, 2849577838, 13758978926, 66434227054, 320772823918, 1548828203886, 7478404111214, 36108929260398, 174349333486446, 841833050987374, 4064729537895278
Offset: 1

Views

Author

Clark Kimberling, Feb 13 2021

Keywords

Crossrefs

Programs

  • Mathematica
    z = 40; r = Sqrt[2]; s = 2 + Sqrt[2]; f[x_] := Floor[r*Floor[s*x]];
    Table[f[n], {n, 1, z}] (* A022804 *)
    a[1] = 1; a[n_] := f[a[n - 1]];
    t = Table[a[n], {n, 1, z}] (* A341248 *)

Formula

Let f(n) = floor(r*floor(s*n)) = A022804(n), where r = sqrt(2) and s = r + 2. Let a(1) = 1. Then a(n) = f(a(n-1)) for n >= 2.
G.f.: x*(1 - x - 2*x^2)/(1 - 5*x + 4*x^3). - Stefano Spezia, Feb 13 2021
Showing 1-4 of 4 results.