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 1-6 of 6 results.

A164086 Beatty sequence for 4*Pi/3 = 4.1887902... .

Original entry on oeis.org

4, 8, 12, 16, 20, 25, 29, 33, 37, 41, 46, 50, 54, 58, 62, 67, 71, 75, 79, 83, 87, 92, 96, 100, 104, 108, 113, 117, 121, 125, 129, 134, 138, 142, 146, 150, 154, 159, 163, 167, 171, 175, 180, 184, 188, 192, 196, 201, 205, 209, 213, 217, 222, 226, 230, 234, 238, 242
Offset: 1

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Author

Reinhard Zumkeller, Aug 11 2009

Keywords

Comments

a(n) = A109238(n) for n <= 20;
complement of A164087;
a(n) = A164088(A164087(n)) and A164088(a(n)) = A164087(n);
a(A000578(n)) = A066645(n).

Examples

			a(3^3) = a(27) = 113 = (integer part of volume of sphere with radius=3) = A066645(3).
		

Crossrefs

Programs

Formula

a(n) = floor(4*n*Pi/3).

A135973 Ceiling(4/3*Pi*n^3).

Original entry on oeis.org

0, 5, 34, 114, 269, 524, 905, 1437, 2145, 3054, 4189, 5576, 7239, 9203, 11495, 14138, 17158, 20580, 24430, 28731, 33511, 38793, 44603, 50966, 57906, 65450, 73623, 82448, 91953, 102161, 113098, 124789, 137259, 150533, 164637, 179595, 195433
Offset: 0

Views

Author

Mohammad K. Azarian, Mar 02 2008

Keywords

Comments

Volume of a sphere of radius n, rounded up.

Crossrefs

Programs

  • Mathematica
    Table[Ceiling[4/3*Pi * n^3], {n, 0, 60}] (* Vincenzo Librandi, Feb 19 2013 *)
  • PARI
    a(n)=ceil(4/3*Pi*n^3) \\ Charles R Greathouse IV, Oct 10 2013
  • Sage
    n=100 # change n for more values
    [ceil(4/3*pi*r^3) for r in [0..n]] # Tom Edgar, Oct 10 2013
    

Formula

a(n) = A066645(n) + 1 for n > 0.

Extensions

Definition replaced by Vincenzo Librandi, Feb 19 2013
0 prepended by T. D. Noe, Oct 10 2013

A228272 Volume of sphere (rounded down) with the diameter equal to n.

Original entry on oeis.org

0, 4, 14, 33, 65, 113, 179, 268, 381, 523, 696, 904, 1150, 1436, 1767, 2144, 2572, 3053, 3591, 4188, 4849, 5575, 6370, 7238, 8181, 9202, 10305, 11494, 12770, 14137, 15598, 17157, 18816, 20579, 22449, 24429, 26521, 28730, 31059, 33510, 36086, 38792, 41629, 44602
Offset: 1

Views

Author

K. D. Bajpai, Aug 19 2013

Keywords

Examples

			a(6)=113 since volume is (Pi*n^3)/6 = Pi*6^3/6 = 113.0973355 and floor(113.0973355) = 113.
		

Crossrefs

Cf. A019673 (Pi/6).
Cf. A066645 (volume with radius n).
Cf. A228189 (similar sequence for right circular cone).

Programs

  • Maple
    a:= n-> floor((Pi*n^3)/6):
    seq(a(n),  n=1..100);

Formula

a(n) = floor((Pi*n^3)/6).

A135971 Ceiling(4*Pi*n^2).

Original entry on oeis.org

13, 51, 114, 202, 315, 453, 616, 805, 1018, 1257, 1521, 1810, 2124, 2464, 2828, 3217, 3632, 4072, 4537, 5027, 5542, 6083, 6648, 7239, 7854, 8495, 9161, 9853, 10569, 11310, 12077, 12868, 13685, 14527, 15394, 16287, 17204, 18146, 19114, 20107
Offset: 1

Views

Author

Mohammad K. Azarian, Mar 02 2008

Keywords

Comments

The original definition was "a(n)=ceiling[surface area of a shpere of radius n]".

Crossrefs

Programs

  • Mathematica
    Table[Ceiling[4 Pi n^2], {n, 1, 50}] (* Vincenzo Librandi, Feb 19 2013 *)

Extensions

Definition replaced by Bruno Berselli, Feb 19 2013

A297839 Numbers k > 0 that set a new record for the closeness of (4/3)*Pi*k^3 to an integer.

Original entry on oeis.org

1, 3, 4, 14, 18, 23, 62, 95, 423, 5339, 12352, 108359, 129805, 5334194, 82007322, 90401717, 199671691, 434184265, 655956850, 44438886071
Offset: 1

Views

Author

Felix Fröhlich, Jan 07 2018

Keywords

Comments

Integer radii such that the volume of the corresponding sphere is closer to an integer than for any smaller integer radius.

Examples

			k       | (4/3)*Pi*k^3                             | Deviation from integer
---------------------------------------------------------------------------
1       |                     4.188790204786390... | 0.188790204786390...
3       |                   113.097335529232556... | 0.097335529232556...
4       |                   268.082573106329023... | 0.082573106329023...
14      |                 11494.040321933856861... | 0.040321933856861...
18      |                 24429.024474314232222... | 0.024474314232222...
23      |                 50965.010421636019109... | 0.010421636019109...
62      |                998305.991926330990581... | 0.008073669009418...
95      |               3591364.001828731970435... | 0.001828731970435...
423     |             317036825.999590816501793... | 0.000409183498206...
5339    |          637482653747.999839504336479... | 0.000160495663520...
12352   |         7894060641354.000003942767448... | 0.000003942767448...
108359  |      5329464512150064.999997849950689... | 0.000000215004931...
129805  |      9161421693208264.000000035388795... | 0.000000035388795...
5334194 | 635762677398025211698.999999995151941... | 0.000000004848058...
		

Crossrefs

Programs

  • PARI
    closeness(n) = my(v=(4/3)*Pi*n^3); if(round(v) > v, return(round(v)-v), return(v-round(v)))
    my(r=1, k=1, c=0); while(1, c=closeness(k); if(c < r, print1(k, ", "); r=c); k++)

Extensions

a(15)-a(19) from Jon E. Schoenfield, Jan 07 2018
a(20) from David Consiglio, Jr., Mar 14 2023

A210519 a(n) = floor(volume of 4-sphere of radius n).

Original entry on oeis.org

0, 4, 78, 399, 1263, 3084, 6395, 11848, 20212, 32377, 49348, 72250, 102328, 140942, 189575, 249824, 323407, 412159, 518035, 643108, 789568, 959725, 1156007, 1380959, 1637248, 1927657, 2255086, 2622556, 3033205, 3490291
Offset: 0

Views

Author

Jon Perry, Jan 26 2013

Keywords

Comments

The 4-sphere here refers to the geometric sphere, that is, 4 refers to the number of dimensions of the sphere.
The general formula for the volume of an n-sphere can be derived using (4)-(10) at the Mathworld link, and some explicit values for higher dimensional spheres are given at the Wikipedia link, section 2.4. Note that Wikipedia uses the topologic definition and calls this 4-sphere a 3-sphere.

Crossrefs

Programs

  • JavaScript
    pi = Math.PI;
    for (i = 0; i < 60; i++) document.write(Math.floor(pi*pi*i*i*i*i/2) + ", ");
  • Mathematica
    Table[Floor[(Pi^2 n^4)/2], {n, 0, 29}]

Formula

a(n) = floor(1/2*Pi^2*n^4).
Showing 1-6 of 6 results.