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 1-5 of 5 results.

A190509 a(n) = n + [nr/s] + [nt/s] + [nu/s] where r=golden ratio, s=r^2, t=r^3, u=r^4, and [] represents the floor function.

Original entry on oeis.org

4, 11, 15, 22, 29, 33, 40, 44, 51, 58, 62, 69, 76, 80, 87, 91, 98, 105, 109, 116, 120, 127, 134, 138, 145, 152, 156, 163, 167, 174, 181, 185, 192, 199, 203, 210, 214, 221, 228, 232, 239, 243, 250, 257, 261, 268, 275, 279, 286, 290, 297, 304, 308, 315, 319, 326, 333, 337, 344, 351, 355, 362, 366, 373, 380, 384, 391, 398, 402, 409
Offset: 1

Views

Author

Clark Kimberling, May 11 2011

Keywords

Comments

See A190508.
From Clark Kimberling, Nov 13 2022: (Start)
This is the third of four sequences that partition the positive integers. Suppose that u = (u(n)) and v = (v(n)) are increasing sequences of positive integers. Let u' and v' be their (increasing) complements, and consider these four sequences:
(1) v o u, defined by (v o u)(n) = v(u(n));
(2) u o v';
(3) v o u';
(4) v' o u'.
Every positive integer is in exactly one of the four sequences. For the reverse composites, u o v, u o v', u' o v, u' o v', see A356104 to A356107.
Assume that if w is any of the sequences u, v, u', v', then lim_{n->oo} w(n)/n exists and defines the (limiting) density of w. For w = u,v,u',v', denote the densities by r,s,r',s'. Then the densities of sequences (1)-(4) exist, and
1/(r*r') + 1/(r*s') + 1/(s*s') + 1/(s*r') = 1.
For this sequence, u, v, u', v', are the Beatty sequences given by u(n) = floor(n*(1+sqrt(5))/2) and v(n) = floor(n*sqrt(5)), so that r = (1+sqrt(5))/2, s = sqrt(5), r' = (3+sqrt(5))/2, s' = (5 + sqrt(5))/4.
(1) v o u = (2, 6, 8, 13, 17, 20, 24, 26, 31, 35, 38, 42, ...) = A356217
(2) v' o u = (1, 5, 7, 10, 14, 16, 19, 21, 25, 28, 30, 34, ...) = A356218
(3) v o u' = (4, 11, 15, 22, 29, 33, 40, 44, 51, 58, 62, 76, ...) = this sequence
(4) v' o u' = (3, 9, 12, 18, 23, 27, 32, 36, 41, 47, 50, 56, ...) = A356220
(End)

Crossrefs

Programs

  • Magma
    [3*Floor(n*(Sqrt(5)+1)/2) + n: n in [1..80]]; // Vincenzo Librandi, Nov 01 2018
    
  • Maple
    r:=(1+sqrt(5))/2: s:=r^2: t:=r^3: u:=r^4: a:=n->n+floor(n*r/s)+floor(n*t/s)+floor(n*u/s):  seq(a(n),n=1..70); # Muniru A Asiru, Nov 01 2018
  • Mathematica
    (See A190508.)
    Table[3 Floor[n (Sqrt[5] + 1) / 2] + n, {n, 1, 100}] (* Vincenzo Librandi, Nov 01 2018 *)
  • PARI
    a(n) = 3*floor(n*(sqrt(5)+1)/2) + n; \\ Michel Marcus, Sep 10 2017; after Michel Dekking's formula
    
  • Python
    from math import isqrt
    def A190509(n): return n+((m:=n+isqrt(5*n**2))&-2)+(m>>1) # Chai Wah Wu, Aug 10 2022

Formula

A190508: a(n) = n + [nr] + [nr^2] + [nr^3];
A190509: b(n) = [n/r] + n + [nr] + [nr^2];
A054770: c(n) = [n/r^2] + [n/r] + n + [nr];
A190511: d(n) = [n/r^3] + [n/r^2] + [n/r] + n.
a(n) = 3*A000201(n)+n, since r/s = 1/r = r-1, and u/s = r^2 = r+1. - Michel Dekking, Sep 06 2017
a(n) = A000201(n) + A003623(n). - Primoz Pirnat, Jan 08 2021

A356104 a(n) = A000201(A022839(n)).

Original entry on oeis.org

3, 6, 9, 12, 17, 21, 24, 27, 32, 35, 38, 42, 46, 50, 53, 56, 61, 64, 67, 71, 74, 79, 82, 85, 88, 93, 97, 100, 103, 108, 111, 114, 118, 122, 126, 129, 132, 135, 140, 144, 147, 150, 155, 158, 161, 165, 169, 173, 176, 179, 184, 187, 190, 194, 197, 202, 205, 208
Offset: 1

Views

Author

Clark Kimberling, Sep 08 2022

Keywords

Comments

This is the first of four sequences that partition the positive integers. Suppose that u = (u(n)) and v = (v(n)) are increasing sequences of positive integers. Let u' and v' be their (increasing) complements, and consider these four sequences:
(1) u o v, defined by (u o v)(n) = u(v(n));
(2) u o v';
(3) u' o v;
(4) u' o v'.
Every positive integer is in exactly one of the four sequences. For the reverse composites, v o u, v' o u, v o u', v' o u', see A356217 to A356220.
Assume that if w is any of the sequences u, v, u', v', then lim_{n->oo} w(n)/n exists and defines the (limiting) density of w. For w = u,v,u',v', denote the densities by r,s,r',s'. Then the densities of sequences (1)-(4) exist, and
1/(r*r') + 1/(r*s') + 1/(s*s') + 1/(s*r') = 1.
For A356104, u, v, u', v', are the Beatty sequences given by u(n) = floor(n*(1+sqrt(5))/2) and v(n) = floor(n*sqrt(5)), so r = (1+sqrt(5))/2, s = sqrt(5), r' = (3+sqrt(5))/2, s' = (5 + sqrt(5))/4.

Examples

			(1)  u o v = (3, 6, 9, 12, 17, 21, 24, 27, 32, 35, 38, 42, 46, ...) = A356104
(2)  u o v' = (1, 4, 8, 11, 14, 16, 19, 22, 25, 29, 30, 33, 37, ...) = A356105
(3)  u' o v = (5, 10, 15, 20, 28, 34, 39, 44, 52, 57, 62, 68, ...) = A356106
(4)  u' o v' = (2, 7, 13, 18, 23, 26, 31, 36, 41, 47, 49, 54, ...) = A356107
		

Crossrefs

Cf. u = A000201, u' = A001950, v = A022839, v' = A108598, A356105, A356106, A356107, A351415 (intersections), A356217 (reverse composites).

Programs

  • Mathematica
    z = 1000;
    u = Table[Floor[n*(1 + Sqrt[5])/2], {n, 1, z}];  (* A000201 *)
    u1 = Complement[Range[Max[u]], u];  (* A001950 *)
    v = Table[Floor[n*Sqrt[5]], {n, 1, z}];  (* A022839 *)
    v1 = Complement[Range[Max[v]], v];  (* A108598 *)
    zz = 120;
    Table[u[[v[[n]]]], {n, 1, zz}]    (* A356104 *)
    Table[u[[v1[[n]]]], {n, 1, zz}]   (* A356105 *)
    Table[u1[[v[[n]]]], {n, 1, zz}]   (* A356106 *)
    Table[u1[[v1[[n]]]], {n, 1, zz}]  (* A356107 *)

A356217 a(n) = A022839(A000201(n)).

Original entry on oeis.org

2, 6, 8, 13, 17, 20, 24, 26, 31, 35, 38, 42, 46, 49, 53, 55, 60, 64, 67, 71, 73, 78, 82, 84, 89, 93, 96, 100, 102, 107, 111, 114, 118, 122, 125, 129, 131, 136, 140, 143, 147, 149, 154, 158, 160, 165, 169, 172, 176, 178, 183, 187, 190, 194, 196, 201, 205, 207
Offset: 1

Views

Author

Clark Kimberling, Oct 02 2022

Keywords

Comments

This is the first of four sequences that partition the positive integers. Suppose that u = (u(n)) and v = (v(n)) are increasing sequences of positive integers. Let u' and v' be their (increasing) complements, and consider these four sequences:
(1) v o u, defined by (v o u)(n) = v(u(n));
(2) v' o u;
(3) v o u';
(4) v' o u'.
Every positive integer is in exactly one of the four sequences. For the reverse composites, u o v, u o v', u' o v, u' o v', see A356104 to A356107.
Assume that if w is any of the sequences u, v, u', v', then lim_{n->oo} w(n)/n exists and defines the (limiting) density of w. For w = u,v,u',v', denote the densities by r,s,r',s'. Then the densities of sequences (1)-(4) exist, and
1/(r*r') + 1/(r*s') + 1/(s*s') + 1/(s*r') = 1.
For A356217 u, v, u', v', are the Beatty sequences given by u(n) = floor(n*(1+sqrt(5))/2) and v(n) = floor(n*sqrt(5)), so that r = (1+sqrt(5))/2, s = sqrt(5), r' = (3+sqrt(5))/2, s' = (5 + sqrt(5))/4.

Examples

			(1)  v o u = (2, 6, 8, 13, 17, 20, 24, 26, 31, 35, 38, 42, ...) = A356217
(2)  v' o u = (1, 5, 7, 10, 14, 16, 19, 21, 25, 28, 30, 34, ...) = A356218
(3)  v o u' = (4, 11, 15, 22, 29, 33, 40, 44, 51, 58, 62, 76, ...) = A190509
(4)  v' o u' = (3, 9, 12, 18, 23, 27, 32, 36, 41, 47, 50, 56, ...) = A356220
		

Crossrefs

Cf. u = A000201, u' = A001950, v = A022839, v' = A108598, A351415 (intersections), A356104 (reverse composites), A356218, A190509, A356220.

Programs

  • Mathematica
    z = 1000;
    u = Table[Floor[n*(1 + Sqrt[5])/2], {n, 1, z}];  (* A000201 *)
    u1 = Complement[Range[Max[u]], u];  (* A001950 *)
    v = Table[Floor[n*Sqrt[5]], {n, 1, z}];  (* A022839 *)
    v1 = Complement[Range[Max[v]], v];  (* A108598 *)
    Table[v[[u[[n]]]], {n, 1, z/4}]   (* A356217 *)
    Table[v1[[u[[n]]]], {n, 1, z/4}]  (* A356218 *)
    Table[v[[u1[[n]]]], {n, 1, z/4}]  (* A190509 *)
    Table[v1[[u1[[n]]]], {n, 1, z/4}] (* A356220 *)
  • Python
    from math import isqrt
    def A356217(n): return isqrt(5*(n+isqrt(5*n**2)>>1)**2) # Chai Wah Wu, Oct 14 2022

A356105 a(n) = A000201(A108598(n)).

Original entry on oeis.org

1, 4, 8, 11, 14, 16, 19, 22, 25, 29, 30, 33, 37, 40, 43, 45, 48, 51, 55, 58, 59, 63, 66, 69, 72, 76, 77, 80, 84, 87, 90, 92, 95, 98, 101, 105, 106, 110, 113, 116, 119, 121, 124, 127, 131, 134, 137, 139, 142, 145, 148, 152, 153, 156, 160, 163, 166, 168, 171
Offset: 1

Views

Author

Clark Kimberling, Sep 08 2022

Keywords

Comments

This is the second of four sequences that partition the positive integers. See A356104.

Examples

			(1)  u o v = (3, 6, 9, 12, 17, 21, 24, 27, 32, 35, 38, 42, 46, ...) = A356104
(2)  u o v' = (1, 4, 8, 11, 14, 16, 19, 22, 25, 29, 30, 33, 37, ...) = A356105
(3)  u' o v = (5, 10, 15, 20, 28, 34, 39, 44, 52, 57, 62, 68, ...) = A356106
(4)  u' o v' = (2, 7, 13, 18, 23, 26, 31, 36, 41, 47, 49, 54, ...) = A356107
		

Crossrefs

Cf. u = A000201, u' = A001950, v = A022839, v' = A108598, A356104, A356106, A356107, A351415 (intersections), A356217 (reverse composites).

Programs

  • Mathematica
    z = 1000;
    u = Table[Floor[n*(1 + Sqrt[5])/2], {n, 1, z}];  (* A000201 *)
    u1 = Complement[Range[Max[u]], u];  (* A001950 *)
    v = Table[Floor[n*Sqrt[5]], {n, 1, z}];  (* A022839 *)
    v1 = Complement[Range[Max[v]], v];  (* A108598 *)
    zz = 120;
    Table[u[[v[[n]]]], {n, 1, zz}]    (* A356104 *)
    Table[u[[v1[[n]]]], {n, 1, zz}]   (* A356105 *)
    Table[u1[[v[[n]]]], {n, 1, zz}]   (* A356106 *)
    Table[u1[[v1[[n]]]], {n, 1, zz}]  (* A356107 *)

A356106 a(n) = A001950(A022839(n)).

Original entry on oeis.org

5, 10, 15, 20, 28, 34, 39, 44, 52, 57, 62, 68, 75, 81, 86, 91, 99, 104, 109, 115, 120, 128, 133, 138, 143, 151, 157, 162, 167, 175, 180, 185, 191, 198, 204, 209, 214, 219, 227, 233, 238, 243, 251, 256, 261, 267, 274, 280, 285, 290, 298, 303, 308, 314, 319
Offset: 1

Views

Author

Clark Kimberling, Sep 08 2022

Keywords

Comments

This is the third of four sequences that partition the positive integers. See A356104.

Examples

			(1)  u o v = (3, 6, 9, 12, 17, 21, 24, 27, 32, 35, 38, 42, 46, ...) = A356104
(2)  u o v' = (1, 4, 8, 11, 14, 16, 19, 22, 25, 29, 30, 33, 37, ...) = A356105
(3)  u' o v = (5, 10, 15, 20, 28, 34, 39, 44, 52, 57, 62, 68, ...) = this sequence
(4)  u' o v' = (2, 7, 13, 18, 23, 26, 31, 36, 41, 47, 49, 54, ...) = A356107
		

Crossrefs

Cf. u = A000201, u' = A001950, v = A022839, v' = A108598, A356104, A356105, A356107, A351415 (intersections), A356217 (reverse composites).

Programs

  • Mathematica
    z = 1000;
    u = Table[Floor[n*(1 + Sqrt[5])/2], {n, 1, z}];  (* A000201 *)
    u1 = Complement[Range[Max[u]], u];  (* A001950 *)
    v = Table[Floor[n*Sqrt[5]], {n, 1, z}];  (* A022839 *)
    v1 = Complement[Range[Max[v]], v];  (* A108598 *)
    zz = 120;
    Table[u[[v[[n]]]], {n, 1, zz}]    (* A356104 *)
    Table[u[[v1[[n]]]], {n, 1, zz}]   (* A356105 *)
    Table[u1[[v[[n]]]], {n, 1, zz}]   (* this sequence *)
    Table[u1[[v1[[n]]]], {n, 1, zz}]  (* A356107 *)

Extensions

Definition corrected by Georg Fischer, May 24 2024
Showing 1-5 of 5 results.