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.

A062278 a(n) = floor(3^n / n^3).

Original entry on oeis.org

3, 1, 1, 1, 1, 3, 6, 12, 27, 59, 133, 307, 725, 1743, 4251, 10509, 26285, 66430, 169450, 435848, 1129505, 2947131, 7737583, 20430377, 54226471, 144621405, 387420489, 1042127936, 2813988985, 7625597484, 20733556989, 56549688380
Offset: 1

Views

Author

Henry Bottomley, Jul 02 2001

Keywords

Comments

3 is the only integer value of k for which floor(n^k / k^n) is always positive. For positive real x and k, the only value of k for which x^k is always greater than or equal to k^x is e = 2.71828...

Examples

			a(2) = floor(3^2 / 2^3) = floor(9/8) = 1.
		

Crossrefs

Programs

A233441 a(n) = floor(2^n / n^3).

Original entry on oeis.org

2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 3, 5, 9, 16, 26, 44, 76, 131, 226, 393, 689, 1213, 2147, 3818, 6818, 12228, 22012, 39768, 72084, 131072, 239027, 437102, 801393, 1472896, 2713342, 5009438, 9267786, 17179869, 31906432, 59362467, 110632938, 206519839, 386111079
Offset: 1

Views

Author

Alex Ratushnyak, Dec 09 2013

Keywords

Crossrefs

Programs

  • Mathematica
    Array[Floor[2^#/#^3] &, 50] (* Paolo Xausa, Mar 27 2025 *)
  • Python
    for n in range(1,100):  print(2**n // n**3, end=', ')

Formula

a(n) = floor(A000079(n) / A000578(n)).

A215894 a(n) = floor(2^n / n^k), where k is the largest integer such that 2^n >= n^k.

Original entry on oeis.org

1, 2, 1, 1, 1, 2, 4, 6, 1, 1, 2, 3, 5, 9, 1, 1, 2, 4, 6, 10, 17, 1, 2, 3, 5, 9, 15, 26, 1, 2, 4, 6, 11, 18, 31, 1, 2, 4, 6, 11, 19, 32, 1, 2, 3, 5, 9, 16, 28, 49, 1, 2, 4, 7, 13, 22, 38, 1, 1, 3, 5, 9, 16, 27, 47, 1, 2, 3, 5, 10, 17, 30, 51, 1, 2, 3, 5, 10
Offset: 2

Views

Author

Alex Ratushnyak, Aug 25 2012

Keywords

Comments

a(n) < n.
n such that a(n) = n-1: 2, 3, 996, 3389, 149462.

Examples

			a(2) = floor(2^2 / 2^2) = 1,
a(3) = floor(2^3 / 3) = 2,
a(4)..a(9) are floor(2^n / n^2),
a(10)..a(15) are floor(2^n / n^3),
a(16)..a(22) are floor(2^n / n^4), and so on.
		

Crossrefs

Programs

  • Magma
    [Floor(2^n div n^Floor(n *Log(n,2))): n in [2..100]]; // Vincenzo Librandi, Jan 09 2019
  • Mathematica
    Table[Floor[2^n/n^Floor[n Log[n, 2]]], {n, 2, 64}] (* Alonso del Arte, Aug 26 2012 *)
  • Python
    import math
    def modiv(a,b):
        return a - b*(a//b)
    def modlg(a,b):
        return a // b**int(math.log(a,b))
    for n in range(2,100):
        a = 2**n
        print(modlg(a,n), end=',')
    

Formula

a(n) = modlg(2^n, n) = floor(2^n / n^floor(n*logn(2))), where logn is the logarithm base n.
In the base-b representation of k, modlg(k,b) is the most significant digit: k = c0 + c1*b + c2*b^2 + ... + cn*b^n, cn = modlg(k,b), c0 = k mod b. - Alex Ratushnyak, Aug 30 2012

A230664 a(n) = floor(3^n/n^2).

Original entry on oeis.org

3, 2, 3, 5, 9, 20, 44, 102, 243, 590, 1464, 3690, 9433, 24402, 63772, 168151, 446851, 1195742, 3219560, 8716961, 23719621, 64836900, 177964421, 490329056, 1355661775, 3760156550, 10460353203, 29179582212, 81605680576, 228767924549, 642740266684, 1809590028175
Offset: 1

Views

Author

Alex Ratushnyak, Dec 11 2013

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Floor[3^n/n^2], {n, 40}] (* Wesley Ivan Hurt, Apr 25 2023 *)
  • Python
    for n in range(1,100):  print(3**n // n**2, end=", ")

Formula

a(n) = floor(A000244(n)/A000290(n)).

A062283 Square array read by descending antidiagonals: T(n,k) = floor(n^k/k^n).

Original entry on oeis.org

1, 0, 2, 0, 1, 3, 0, 0, 1, 4, 0, 1, 1, 1, 5, 0, 1, 1, 0, 0, 6, 0, 1, 1, 1, 0, 0, 7, 0, 2, 3, 1, 0, 0, 0, 8, 0, 4, 6, 3, 1, 0, 0, 0, 9, 0, 6, 12, 6, 2, 0, 0, 0, 0, 10, 0, 10, 27, 16, 4, 1, 0, 0, 0, 0, 11, 0, 16, 59, 39, 11, 2, 0, 0, 0, 0, 0, 12, 0, 28, 133, 104, 33, 6, 1, 0, 0, 0, 0, 0, 13
Offset: 1

Views

Author

Henry Bottomley, Jul 02 2001

Keywords

Examples

			T(3,2) = floor(3^2/2^3) = floor(9/8) = 1.
		

Crossrefs

Programs

  • Mathematica
    Table[Floor[k^(n-k+1)/(n-k+1)^k], {n, 15}, {k, n}] (* Paolo Xausa, May 06 2024 *)
Showing 1-5 of 5 results.