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 1-10 of 13 results. Next

A100731 a(n) = 3^(n!).

Original entry on oeis.org

3, 3, 9, 729, 282429536481, 1797010299914431210413179829509605039731475627537851106401
Offset: 0

Views

Author

Parthasarathy Nambi, Jan 12 2005

Keywords

Examples

			If n=2, 3^(2!) = 9.
If n=3, 3^(3!) = 729.
If n=4, 3^(4!) = 282429536481.
		

Crossrefs

Programs

Formula

From Vincenzo Librandi, Dec 16 2012: (Start)
a(n) = a(n-1)^n, a(0)=3.
a(n) = A000244(A000142(n)). (End)

A053986 a(n) = n^(n!).

Original entry on oeis.org

0, 1, 4, 729, 281474976710656, 752316384526264005099991383822237233803945956334136013765601092018187046051025390625
Offset: 0

Views

Author

Henry Bottomley, Apr 03 2000

Keywords

Comments

Next term has 561 digits.

Examples

			a(3) = 729 because 3^3! = 3^6 = 729.
		

Crossrefs

Programs

  • Mathematica
    Table[n^n!, {n, 0, 5}] (* Alonso del Arte, Jan 03 2011 *)
  • Maxima
    makelist(n^n!,n,0,6); /* Martin Ettl, Jan 13 2013 */

Formula

Sum_{n>=1} 1/a(n) = A100084. - Amiram Eldar, Nov 11 2020

Extensions

One more term from Lior Manor, Nov 27 2001

A076187 Decimal expansion of Sum_{k>=0} 1/2^(k!).

Original entry on oeis.org

1, 2, 6, 5, 6, 2, 5, 0, 5, 9, 6, 0, 4, 6, 4, 4, 7, 7, 5, 3, 9, 0, 6, 2, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 5, 2, 3, 1, 6, 3, 8, 4, 5, 2, 6, 2, 6, 4, 0, 0, 5, 0, 9, 9, 9, 9, 1, 3, 8, 3, 8, 2, 2, 2, 3, 7, 2, 3, 3, 8, 0, 3, 9, 4, 5, 9, 5, 6, 3, 3, 4, 1, 3, 6, 0, 1, 3, 7, 6, 5, 6, 0, 1, 0, 9, 2, 0, 1, 8, 1, 8
Offset: 1

Views

Author

Benoit Cloitre, Nov 02 2002

Keywords

Examples

			1.2656250596046447753906250000000000007...
		

Crossrefs

Programs

  • Mathematica
    digits = 105; NSum[ 1/2^k!, {k, 0, 12} , WorkingPrecision -> digits] // RealDigits[#, 10, digits]& // First (* Jean-François Alcover, Mar 04 2013 *)
    RealDigits[Total[1/2^Range[0,10]!],10,120][[1]] (* Harvey P. Dale, Oct 16 2024 *)
  • PARI
    suminf(k=0, 1/2^(k!)) \\ Michel Marcus, Feb 19 2021

Formula

Equals Sum_{k>=0} 1/A050923(k).
Equals A092874 plus 0.5. [R. J. Mathar, Sep 08 2008]

A317873 Number of digits in 2^(n!).

Original entry on oeis.org

1, 1, 1, 2, 8, 37, 217, 1518, 12138, 109238, 1092378, 12016155, 144193850, 1874520045, 26243280622, 393649209329, 6298387349264, 107072584937472, 1927306528874488, 36618824048615255, 732376480972305082, 15379906100418406713, 338357934209204947674
Offset: 0

Views

Author

Keywords

Comments

The old definition (which did not match the data) was "Number of digits in the numerators of partial sums for Liouville's constant, read as base-2 (binary) numbers (A145572)."

Crossrefs

Programs

  • Maple
    Digits := 900: # for n <= 300
    a := n -> ceil(exp(lnGAMMA(n + 1))*log10(2)):
    seq(a(n), n = 0..30);  # Peter Luschny, Apr 18 2024
  • Mathematica
    Array[ Floor[#! Log10@2 + 1] &, 22]

Formula

a(n) = A034887(n!).

Extensions

Better definition suggested by Martin Renner, Mar 24 2024
a(0)=1 prepended by Alois P. Heinz, Jul 27 2025

A220078 a(n) = 5^(n!).

Original entry on oeis.org

5, 5, 25, 15625, 59604644775390625, 752316384526264005099991383822237233803945956334136013765601092018187046051025390625
Offset: 0

Views

Author

Vincenzo Librandi, Dec 16 2012

Keywords

Comments

The next term (a(6)) has 504 digits. - Harvey P. Dale, Apr 01 2013

Crossrefs

Programs

  • Magma
    [5^(Factorial(n)): n in [0..7]];
    
  • Mathematica
    lst={}; Do[AppendTo[lst, 5^n!], {n, 0, 9}]; lst
    5^Range[6]! (* Harvey P. Dale, Apr 01 2013 *)
  • Maxima
    makelist(5^(n!),n,0,5); /* Martin Ettl, Dec 27 2012 */

Formula

a(n) = a(n-1)^n, a(0) = 5.
a(n) = A000351(A000142(n)).

Extensions

One more term (a(5)) from Harvey P. Dale, Apr 01 2013

A178981 2^A003418(n); for n >= 1, the least number > 1 that can be expressed simultaneously as a k-th power of some integer for all 1 <= k <= n.

Original entry on oeis.org

2, 2, 4, 64, 4096, 1152921504606846976, 1152921504606846976
Offset: 0

Views

Author

Rick L. Shepherd, Jan 02 2011

Keywords

Comments

Equivalently, for n >= 1, the least number > 1 of objects that can be arranged as a k-cube (k-dimensional hypercube) for all 1 <= k <= n.
a(7) = 2^420 contains 127 decimal digits.
From Jianing Song, Jul 20 2021: (Start)
Let F_q be the finite field with q elements, then F_a(n) is the smallest extension field of F_2 such that every polynomial of degree at most n splits into linear factors.
Union_{n>=0} F_a(n) is the algebraic clousre of F_2, which is the unique algebraically closed field with characteristic 2 and transcendence degree 0 (note that an algebraically closed field is uniquely determined by its characteristic and transcendence degree). Union_{n>=0} F_(2^(n!)) = Union_{n>=0} F_A050923(n) gives the same field.
Obviously, here 2 can be replaced by any prime p provided that {a(n)} is defined as a(n) = p^A003418(n). (End)

Examples

			a(6) = 2^A003418(6) = 2^60 = 1152921504606846976 [= (2^60)^1] = (2^30)^2 = 1073741824^2 = (2^20)^3 = 1048576^3 = (2^15)^4 = 32768^4 = (2^12)^5 = 4096^5 = (2^10)^6 = 1024^6, while no smaller integer > 1 can be expressed simultaneously as a square, cube, 4th, 5th, and 6th power of integers.
		

Crossrefs

Programs

  • PARI
    a(n)=2^(lcm(vector(n, i, i))) \\ Jianing Song, Jul 20 2021, following a PARI program for A003418

A203925 3^n! - 2^n!.

Original entry on oeis.org

1, 1, 5, 665, 282412759265, 1797010299914431210411850601513820123858571820477570761825
Offset: 0

Views

Author

Assoul Abdelkarim, Jan 08 2012

Keywords

Formula

a(n) = A100731(n) - A050923(n). - Michel Marcus, Sep 04 2013

A220079 a(n) = 7^(n!).

Original entry on oeis.org

7, 7, 49, 117649, 191581231380566414401
Offset: 0

Views

Author

Vincenzo Librandi, Dec 16 2012

Keywords

Crossrefs

Programs

  • Magma
    [7^Factorial(n): n in [0..7]];
    
  • Mathematica
    Table[7^(n!), {n, 0, 7}]
  • Maxima
    makelist(7^(n!),n,0,5); /* Martin Ettl, Dec 27 2012 */

Formula

a(n) = a(n-1)^n, a(0) = 7.
a(n) = A000420(A000142(n)).

A362766 Number of nonisomorphic sets of permutations of an n-set.

Original entry on oeis.org

2, 2, 4, 24, 711936, 11076899964874307395625695676727296
Offset: 0

Views

Author

Andrew Howroyd, May 03 2023

Keywords

Comments

Isomorphism is up to permutation of the elements of the n-set.
a(6) has 214 decimal digits.

Examples

			The a(2)=4 sets with permutations shown in cycle notation are:
  {},
  {(1)(2)},
  {(12)},
  {(1)(2), (12)}.
		

Crossrefs

Row sums of A362763.
Cf. A050923.

Formula

a(n) = Sum_{k=0..n!} A362763(n,k).
A050923(n) / n! <= a(n) <= A050923(n).

A305851 a(n) = (a(n-1)+a(n-2))^(n-2) with a(1)=a(2)=1.

Original entry on oeis.org

1, 1, 2, 9, 1331, 3224179360000, 348414297354956334043085401797347258376901025074126347562215651
Offset: 1

Views

Author

Yigithan TAMER, Jun 11 2018

Keywords

Comments

a(8) has 376 digits, a(9) has 2627 digits, a(10) has 21015 digits, see b-file and a-file. - Eric Chen, Jun 14 2018

Crossrefs

Cf. A050923.

Programs

  • Mathematica
    Nest[Append[#, (#[[-1]] + #[[-2]] )^(Length@ # - 2)] &, {1, 1}, 6] (* Michael De Vlieger, Jun 11 2018 *)
    RecurrenceTable[{a[n] == (a[n-1] + a[n-2])^(n-2), a[1] == 1, a[2] == 1}, a, {n, 1, 7}] (* Vaclav Kotesovec, Jul 23 2018 *)
    nxt[{n_,a_,b_}]:={n+1,b,(a+b)^(n-1)}; NestList[nxt,{1,1,1},7][[All,2]] (* Harvey P. Dale, Nov 03 2022 *)
  • PARI
    a(n)=if(n<3,1,(a(n-1)+a(n-2))^(n-2)) \\ Eric Chen, Jun 14 2018
  • Python
    #Generates and prints a list containing the terms, up to the term with the index of seq_limit
    seq_limit=9
    seq_list=[1,1]
    for seq_no in range(3,seq_limit):
        seq_list.append((seq_list[-1]+seq_list[-2])**(seq_no-2))
    print(seq_list)
    

Formula

a(n) ~ c^((n-2)!), where c = 3.3203520468282576446980958620234685911457954899308569085994... - Vaclav Kotesovec, Jul 23 2018
Showing 1-10 of 13 results. Next