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 1-7 of 7 results.

A022844 a(n) = floor(n*Pi).

Original entry on oeis.org

0, 3, 6, 9, 12, 15, 18, 21, 25, 28, 31, 34, 37, 40, 43, 47, 50, 53, 56, 59, 62, 65, 69, 72, 75, 78, 81, 84, 87, 91, 94, 97, 100, 103, 106, 109, 113, 116, 119, 122, 125, 128, 131, 135, 138, 141, 144, 147, 150, 153, 157, 160, 163, 166, 169, 172, 175, 179, 182, 185, 188, 191, 194
Offset: 0

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Author

Keywords

Comments

Beatty sequence for Pi.
Differs from A127451 first at a(57). - L. Edson Jeffery, Dec 01 2013
These are the nonnegative integers m satisfying sin(m)*sin(m+1) <= 0. In general, the Beatty sequence of an irrational number r > 1 consists of the numbers m satisfying sin(m*x)*sin((m+1)*x) <= 0, where x = Pi/r. Thus the numbers m satisfying sin(m*x)*sin((m+1)*x) > 0 form the Beatty sequence of r/(1-r). - Clark Kimberling, Aug 21 2014
This can also be stated in terms of the tangent function. These are the nonnegative integers m such that tan(m/2)*tan(m/2+1/2) <= 0. In general, the Beatty sequence of an irrational number r > 1 consists of the numbers m satisfying tan(m*x/2)*tan((m+1)*x/2) <= 0, where x = Pi/r. Thus the numbers m satisfying tan(m*x/2)*tan((m+1)*x/2) > 0 form the Beatty sequence of r/(1-r). - Clark Kimberling, Aug 22 2014

Examples

			a(7)=21 because 7*Pi=21.9911... and a(8)=25 because 8*Pi=25.1327.... a(100000)=314159 because Pi=3.141592...
		

Crossrefs

First differences give A063438.

Programs

  • Magma
    R:=RieldField(10); [Floor(n*Pi(R)): n in [0..80]]; // G. C. Greubel, Sep 28 2018
  • Maple
    a:=n->floor(n*Pi): seq(a(n),n=0..70); # Muniru A Asiru, Sep 28 2018
  • Mathematica
    Floor[Pi Range[0,200]] (* Harvey P. Dale, Aug 27 2024 *)
  • PARI
    vector(80, n, n--; floor(n*Pi)) \\ G. C. Greubel, Sep 28 2018
    

Formula

a(n)/n converges to Pi because |a(n)/n - Pi| = |a(n) - n*Pi|/n < 1/n. - Hieronymus Fischer, Jan 22 2006

Extensions

Previous Mathematica program replaced by Harvey P. Dale, Aug 27 2024

A054386 Beatty sequence for Pi/(Pi-1); complement of A022844.

Original entry on oeis.org

1, 2, 4, 5, 7, 8, 10, 11, 13, 14, 16, 17, 19, 20, 22, 23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42, 44, 45, 46, 48, 49, 51, 52, 54, 55, 57, 58, 60, 61, 63, 64, 66, 67, 68, 70, 71, 73, 74, 76, 77, 79, 80, 82, 83, 85, 86, 88, 89, 90, 92, 93, 95, 96, 98, 99, 101, 102
Offset: 1

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Keywords

Comments

Differs from A127450 at term n=122, where A054386(122)=178, A127450(122)=179. - Martin Fuller, May 10 2007

Crossrefs

Programs

  • Magma
    R:=RealField(30); [Floor(n*Pi(R)/(Pi(R)-1)): n in [1..80]]; // G. C. Greubel, Oct 22 2023
    
  • Mathematica
    Floor[Pi*Range[80]/(Pi-1)] (* G. C. Greubel, Oct 22 2023 *)
  • SageMath
    [floor(n*pi/(pi-1)) for n in range(1,81)] # G. C. Greubel, Oct 22 2023

A108592 Self-inverse integer permutation induced by Beatty sequences for 2*Pi and 2*Pi/(2*Pi-1).

Original entry on oeis.org

6, 12, 18, 25, 31, 1, 37, 43, 50, 56, 62, 2, 69, 75, 81, 87, 94, 3, 100, 106, 113, 119, 125, 131, 4, 138, 144, 150, 157, 163, 5, 169, 175, 182, 188, 194, 7, 201, 207, 213, 219, 226, 8, 232, 238, 245, 251, 257, 263, 9, 270, 276, 282, 289, 295, 10, 301, 307, 314, 320, 326, 11, 333, 339, 345, 351, 358, 364, 13, 370
Offset: 1

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Author

Reinhard Zumkeller, Jun 11 2005

Keywords

Crossrefs

Programs

  • PARI
    a30(n) = floor(n*2*Pi);
    a86(n) = floor(2*n*Pi/(2*Pi-1));
    lista(nn) = {my(vb = vector(nn, n, a30(n))); my(vc = vector(nn, n, a86(n))); my(va = vector(nn)); for (n=1, nn, if (vb[n] <= nn, va[vb[n]] = vc[n]); if (vc[n] <= nn, va[vc[n]] = vb[n]);); va;} \\ Michel Marcus, May 25 2022

Formula

a(A038130(n))=A108586(n) and a(A108586(n))=A038130(n).

Extensions

Four terms corrected by Georg Fischer and Michel Marcus, May 25 2022

A108590 Self-inverse integer permutation induced by Beatty sequences for Pi/2 and Pi/(Pi-2).

Original entry on oeis.org

2, 1, 5, 8, 3, 11, 13, 4, 16, 19, 6, 22, 7, 24, 27, 9, 30, 33, 10, 35, 38, 12, 41, 14, 44, 46, 15, 49, 52, 17, 55, 57, 18, 60, 20, 63, 66, 21, 68, 71, 23, 74, 77, 25, 79, 26, 82, 85, 28, 88, 90, 29, 93, 96, 31, 99, 32, 101, 104, 34, 107, 110, 36, 112, 115, 37, 118, 39, 121
Offset: 1

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Author

Reinhard Zumkeller, Jun 11 2005

Keywords

Crossrefs

Formula

a(A140758(n))=A108589(n) and a(A108589(n))=A140758(n).

A115239 a(1) = floor(Pi) = 3; a(n+1) = floor(a(n)*Pi).

Original entry on oeis.org

3, 9, 28, 87, 273, 857, 2692, 8457, 26568, 83465, 262213, 823766, 2587937, 8130243, 25541911, 80242279, 252088554, 791959549, 2488014301, 7816327450, 24555716894, 77144059797, 242355211526, 761381352089, 2391950062303
Offset: 1

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Author

Hieronymus Fischer, Jan 17 2006

Keywords

Comments

a(n+1)/a(n) converges to Pi. Similar to sequence A085839 but with a simpler definition.
Subset of the Beatty sequence of Pi = A022844 = floor(n*Pi). Primes in this sequence include a(1) = 3, a(6) = 857, a(15) = 25541911. - Jonathan Vos Post, Jan 18 2006

Examples

			a(2) = floor(a(1)*Pi) = floor(3*Pi) = 9;
a(3) = floor(a(2)*Pi) = floor(9*Pi) = 28;
a(4) = floor(a(3)*Pi) = floor(28*Pi) = 87.
		

Crossrefs

Programs

  • Maple
    A[1]:= 3:
    for n from 2 to 50 do A[n]:= floor(Pi*A[n-1]) od:
    seq(A[i],i=1..50); # Robert Israel, Feb 07 2016
  • Mathematica
    a[1] = Floor[Pi]; a[n_] := a[n] = Floor[a[n - 1]*Pi]; Array[a, 25] (* Robert G. Wilson v, Jan 18 2006 *)
    NestList[Floor[Pi #]&,3,30] (* Harvey P. Dale, Mar 30 2012 *)

Extensions

More terms from Robert G. Wilson v, Jan 18 2006

A108599 Self-inverse integer permutation induced by Beatty sequences for e and e/(e-1).

Original entry on oeis.org

2, 1, 5, 8, 3, 10, 13, 4, 16, 6, 19, 21, 7, 24, 27, 9, 29, 32, 11, 35, 12, 38, 40, 14, 43, 46, 15, 48, 17, 51, 54, 18, 57, 59, 20, 62, 65, 22, 67, 23, 70, 73, 25, 76, 78, 26, 81, 28, 84, 86, 30, 89, 92, 31, 95, 97, 33, 100, 34, 103, 106, 36, 108, 111, 37, 114, 39, 116, 119, 41
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 11 2005

Keywords

Crossrefs

Cf. A108591.

Formula

a(A022843(n))=A054385(n) and a(A054385(n))=A022843(n).

A110119 Self-inverse integer permutation induced by Beatty sequences for x and (x+1)/(2*sqrt(2)) with x=sqrt(2)+sqrt(3).

Original entry on oeis.org

3, 6, 1, 9, 12, 2, 15, 18, 4, 22, 25, 5, 28, 31, 7, 34, 37, 8, 40, 44, 47, 10, 50, 53, 11, 56, 59, 13, 62, 66, 14, 69, 72, 16, 75, 78, 17, 81, 84, 19, 88, 91, 94, 20, 97, 100, 21, 103, 106, 23, 110, 113, 24, 116, 119, 26, 122, 125, 27, 128, 132, 29, 135, 138, 141, 30, 144
Offset: 1

Views

Author

Reinhard Zumkeller, Jul 13 2005

Keywords

Crossrefs

Cf. A135611 (sqrt(2)+sqrt(3)).

Formula

a(A110117(n)) = A110118(n) and a(A110118(n)) = A110117(n).
Showing 1-7 of 7 results.