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.

A022838 Beatty sequence for sqrt(3); complement of A054406.

Original entry on oeis.org

1, 3, 5, 6, 8, 10, 12, 13, 15, 17, 19, 20, 22, 24, 25, 27, 29, 31, 32, 34, 36, 38, 39, 41, 43, 45, 46, 48, 50, 51, 53, 55, 57, 58, 60, 62, 64, 65, 67, 69, 71, 72, 74, 76, 77, 79, 81, 83, 84, 86, 88, 90, 91, 93, 95, 96, 98, 100, 102, 103, 105, 107, 109, 110, 112
Offset: 1

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Author

Keywords

Comments

0 <= A144077(n) - a(n) <= 1. - Reinhard Zumkeller, Sep 09 2008
From Reinhard Zumkeller, Jan 20 2010: (Start)
A080757(n) = a(n+1) - a(n).
A171970(n) = floor(a(n)/2).
A171972(n) = a(A000290(n)). (End)
Numbers k>0 such that A194979(k+1) = A194979(k) + 1. - Clark Kimberling, Dec 02 2014
Powers of 2 (i.e, 1, 8, 32, 64, 128, 256, 512, 4096, 8192,...) appear at n=1, 5, 19, 37, 74, 148, 296, 2365, 4730, 18919, 75675, 151349, 302698, 605396, ... related to A293328. - R. J. Mathar, Jan 17 2025

Crossrefs

Cf. A080757 (first differences), A194106 (partial sums), A194028 (even bisection), A184796 (prime terms).
Cf. A026255, A054406 (complement).

Programs

Formula

a(n) = floor(n*sqrt(3)). - Reinhard Zumkeller, Jan 20 2010
a(n) = 2 * floor(n * (sqrt(3) - 1)) + floor(n * (2 - sqrt(3))) + 1. - Miko Labalan, Dec 03 2016

A171971 Integer part of the area of an equilateral triangle with side length n.

Original entry on oeis.org

0, 1, 3, 6, 10, 15, 21, 27, 35, 43, 52, 62, 73, 84, 97, 110, 125, 140, 156, 173, 190, 209, 229, 249, 270, 292, 315, 339, 364, 389, 416, 443, 471, 500, 530, 561, 592, 625, 658, 692, 727, 763, 800, 838, 876, 916, 956, 997, 1039, 1082, 1126, 1170, 1216, 1262, 1309
Offset: 1

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Author

Reinhard Zumkeller, Jan 20 2010

Keywords

Comments

The Beatty sequence of sqrt(3)/4 starts 0, 0, 1, 1, 2, 2, 3, 3, 3, 4, 4, 5, 5, 6, 6, 6, 7,... for n>=1. This sequence here subsamples the Beatty sequence at the positions of the squares. - R. J. Mathar, Dec 02 2012

Crossrefs

Programs

Formula

a(n) = floor(n^2 * sqrt(3) / 4) = A308358(n^2).
a(n)*A171974(n)/3 <= A171973(n);
A171970(n)*A004526(n) <= a(n).

A171973 Integer part of the volume of a regular tetrahedron with edge length n.

Original entry on oeis.org

0, 0, 3, 7, 14, 25, 40, 60, 85, 117, 156, 203, 258, 323, 397, 482, 579, 687, 808, 942, 1091, 1254, 1433, 1629, 1841, 2071, 2319, 2587, 2874, 3181, 3510, 3861, 4235, 4632, 5052, 5498, 5969, 6466, 6990, 7542, 8122, 8731, 9369, 10039, 10739, 11471, 12235
Offset: 1

Views

Author

Reinhard Zumkeller, Jan 20 2010

Keywords

Comments

Lim{n->oo} a(n)/A000292(n) = sqrt(2)/2;
floor(A171971(n)*A171974(n)/3) <= a(n).

Crossrefs

Programs

  • Haskell
    a171973 = floor . (/ 12) . (* sqrt 2) . fromInteger . a000578
    -- Reinhard Zumkeller, Dec 15 2012

Formula

a(n) = floor(n^3 * sqrt(2) / 12).

A171970 Integer part of the height of an equilateral triangle with side length n.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 6, 7, 8, 9, 10, 11, 12, 12, 13, 14, 15, 16, 17, 18, 19, 19, 20, 21, 22, 23, 24, 25, 25, 26, 27, 28, 29, 30, 31, 32, 32, 33, 34, 35, 36, 37, 38, 38, 39, 40, 41, 42, 43, 44, 45, 45, 46, 47, 48, 49, 50, 51, 51, 52, 53, 54, 55, 56, 57, 58, 58, 59, 60, 61, 62, 63
Offset: 1

Views

Author

Reinhard Zumkeller, Jan 20 2010

Keywords

Crossrefs

Beatty sequence of A010527.

Programs

Formula

a(n) = floor(n*sqrt(3)/2).
a(n) = floor(A022838(n)/2).
a(n)*A004526(n) <= A171971(n)
a(n)*A005843(n) <= A171972(n).

A171974 Integer part of the height of a regular tetrahedron with edge length n.

Original entry on oeis.org

0, 1, 2, 3, 4, 4, 5, 6, 7, 8, 8, 9, 10, 11, 12, 13, 13, 14, 15, 16, 17, 17, 18, 19, 20, 21, 22, 22, 23, 24, 25, 26, 26, 27, 28, 29, 30, 31, 31, 32, 33, 34, 35, 35, 36, 37, 38, 39, 40, 40, 41, 42, 43, 44, 44, 45, 46, 47, 48, 48, 49, 50, 51, 52, 53, 53, 54, 55, 56, 57, 57, 58, 59
Offset: 1

Views

Author

Reinhard Zumkeller, Jan 20 2010

Keywords

Comments

-3 <= 4*A171975(n) - 3*a(n) < 3;
a(n)*A171975(n) <= A007590(n);
floor(a(n)*A171971(n)/3) <= A171973(n).

Crossrefs

Cf. A171972, A022840. Beatty sequence of A157697.

Programs

  • Haskell
    a171974 = floor . (/ 3) . (* sqrt 6) . fromInteger
    -- Reinhard Zumkeller, Dec 15 2012

Formula

a(n) = floor(n*sqrt(6)/3).

A171975 Integer part of the circumsphere radius of a regular tetrahedron with edge length n.

Original entry on oeis.org

0, 1, 1, 2, 3, 3, 4, 4, 5, 6, 6, 7, 7, 8, 9, 9, 10, 11, 11, 12, 12, 13, 14, 14, 15, 15, 16, 17, 17, 18, 18, 19, 20, 20, 21, 22, 22, 23, 23, 24, 25, 25, 26, 26, 27, 28, 28, 29, 30, 30, 31, 31, 32, 33, 33, 34, 34, 35, 36, 36, 37, 37, 38, 39, 39, 40, 41, 41, 42, 42, 43, 44, 44, 45, 45
Offset: 1

Views

Author

Reinhard Zumkeller, Jan 20 2010

Keywords

Comments

-3 <= 4*a(n) - 3*A171974(n) < 3;
a(n)*A171974(n) <= A007590(n).

Crossrefs

Cf. A171973, A171972, A022840. Beatty sequence of A187110.

Programs

  • Haskell
    a171975 = floor . (/ 4) . (* sqrt 6) . fromInteger
    -- Reinhard Zumkeller, Dec 15 2012

Formula

a(n) = floor(n*sqrt(6)/4).

A293410 Least integer k such that k/n^2 > sqrt(3).

Original entry on oeis.org

0, 2, 7, 16, 28, 44, 63, 85, 111, 141, 174, 210, 250, 293, 340, 390, 444, 501, 562, 626, 693, 764, 839, 917, 998, 1083, 1171, 1263, 1358, 1457, 1559, 1665, 1774, 1887, 2003, 2122, 2245, 2372, 2502, 2635, 2772, 2912, 3056, 3203, 3354, 3508, 3666, 3827, 3991
Offset: 0

Views

Author

Clark Kimberling, Oct 11 2017

Keywords

Crossrefs

Programs

  • Mathematica
    z = 120; r = Sqrt[3];
    Table[Floor[r*n^2], {n, 0, z}];   (* A171972 *)
    Table[Ceiling[r*n^2], {n, 0, z}]; (* A293410 *)
    Table[Round[r*n^2], {n, 0, z}];   (* A070169 *)
  • Python
    from math import isqrt
    def A293410(n): return 1+isqrt(3*n**4-1) if n else 0 # Chai Wah Wu, Jul 31 2022

Formula

a(n) = ceiling(r*n^2), where r = sqrt(3).
a(n) = A171972(n) + 1 for n > 0.
Showing 1-7 of 7 results.