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 1-4 of 4 results.

A340810 Triangle T(n,k), n>=2, 2 <= k <= A214046(n), read by rows, where T(n,k) = n! mod k^n.

Original entry on oeis.org

2, 6, 8, 24, 24, 120, 16, 720, 48, 666, 5040, 128, 954, 40320, 384, 8586, 100736, 362880, 768, 26811, 483072, 3628800, 1280, 58725, 2168064, 39916800, 3072, 173259, 9239552, 234860975, 479001600
Offset: 2

Views

Author

Seiichi Manyama, Jan 22 2021

Keywords

Examples

			n\k  |    2       3        4          5          6
-----+---------------------------------------------
   2 |    2;
   3 |    6;
   4 |    8,     24;
   5 |   24,    120;
   6 |   16,    720;
   7 |   48,    666,    5040;
   8 |  128,    954,   40320;
   9 |  384,   8586,  100736,    362880;
  10 |  768,  26811,  483072,   3628800;
  11 | 1280,  58725, 2168064,  39916800;
  12 | 3072, 173259, 9239552, 234860975, 479001600;
		

Crossrefs

Column k=2..4 give A068496, A212309, A212310.

Programs

  • Mathematica
    row[n_] := Module[{k = 1, s = {}}, While[k^n <= n!, k++; AppendTo[s, Mod[n!, k^n]]]; s]; Table[row[n], {n, 2, 12}] // Flatten (* Amiram Eldar, Apr 28 2021 *)
  • Ruby
    def f(n)
      return 1 if n < 2
      (1..n).inject(:*)
    end
    def A(n)
      m = f(n)
      ary = []
      (2..n).each{|i|
        j = i ** n
        ary << m % j
        break if m <= j
      }
      ary
    end
    def A340810(n)
      (2..n).map{|i| A(i)}.flatten
    end
    p A340810(12)

A087375 Smallest n-th power > n!.

Original entry on oeis.org

2, 4, 8, 81, 243, 729, 16384, 65536, 1953125, 9765625, 48828125, 2176782336, 13060694016, 678223072849, 4747561509943, 33232930569601, 2251799813685248, 18014398509481984, 144115188075855872, 12157665459056928801, 109418989131512359209, 10000000000000000000000, 100000000000000000000000, 1000000000000000000000000, 108347059433883722041830251
Offset: 1

Views

Author

Amarnath Murthy, Sep 09 2003

Keywords

Examples

			a(5) = 243 as 243 = 3^5 > 5! > 2^5.
		

Crossrefs

Programs

  • Maple
    g:= proc(n)  floor(1+(n!)^(1/n))^n end proc:
    map(g, [$1..30]); # Robert Israel, Nov 25 2024
  • Mathematica
    a[n_]:=Floor[1+(n!)^(1/n)]^n; Array[a,25] (* Stefano Spezia, Mar 27 2025 *)

Formula

a(n) = A214046(n)^n for n > 1. - Robert Israel, Nov 25 2024

Extensions

Corrected and extended by Mark Hudson (mrmarkhudson(AT)hotmail.com), Aug 25 2004

A214449 Least m>0 such that n! <= m^m.

Original entry on oeis.org

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

Views

Author

Clark Kimberling, Jul 18 2012

Keywords

Comments

Conjecture: this sequence results from A118168 by deleting the first two 1s.

Examples

			a(4) = 3 because 2^2 < 4! < 3^3.
		

Crossrefs

Cf. A214046.

Programs

  • Mathematica
    Table[m = 1; While[n! > m^m, m++]; m, {n, 1, 100}]

A306904 The geometric mean of the first n integers, rounded to the nearest integer.

Original entry on oeis.org

1, 1, 2, 2, 3, 3, 3, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 11, 11, 11, 12, 12, 12, 13, 13, 14, 14, 14, 15, 15, 15, 16, 16, 17, 17, 17, 18, 18, 18, 19, 19, 19, 20, 20, 21, 21, 21, 22, 22, 22, 23, 23, 24, 24, 24, 25, 25, 25
Offset: 1

Views

Author

Robin Powell, Mar 15 2019

Keywords

Comments

a(n) is the least k such that (k-1/2)^n < n!. - Robert Israel, May 05 2019

Examples

			a(5) is the 5th root of the product of the first 5 integers (approx. 2.605171) rounded up to 3.
		

Crossrefs

Cf. A000142, A061375 (floor instead of round), A214046.

Programs

  • Maple
    Res:= 1: last:= 1: v:= 1:
    for n from 2 to 100 do
      v:= n*v; t:= 2^n*v;
      for k from last while (2*k-1)^n < t do od:
      last:= k-1;
      Res:= Res, last;
    od:
    Res; # Robert Israel, May 05 2019
  • Mathematica
    Array[Round[#!^(1/#)] &, 68] (* Michael De Vlieger, Mar 31 2019 *)
    Table[Round[GeometricMean[Range[n]]],{n,70}] (* Harvey P. Dale, Mar 19 2023 *)
  • PARI
    a(n) = round(n!^(1/n)); \\ Michel Marcus, May 05 2019
    
  • Python
    from sympy import integer_nthroot, factorial
    def A306904(n): return (m:=int(integer_nthroot(f:=int(factorial(n)),n)[0]))+int((f<=((m<<1)+1)**n) # Chai Wah Wu, Jun 06 2025

Formula

a(n) = round(n!^(1/n)).
a(n) ~ n/e + log(n)/(2*e). - Robert Israel, May 05 2019

Extensions

Corrected by Robert Israel, May 05 2019
Showing 1-4 of 4 results.