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.

A050923 a(n) = 2^(n!).

Original entry on oeis.org

2, 2, 4, 64, 16777216, 1329227995784915872903807060280344576
Offset: 0

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Author

Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Dec 30 1999

Keywords

Comments

For n > 0, every n-fold repetition of a(n) is a "powerful" arithmetic progression with difference 0; e.g., for n = 4 we get a(4) = 16777216 and in the generated repeating sequence of length 4 the k-th term is a k-th power (1 <= k <= n): 16777216 = 16777216^1, 16777216 = 4096^2, 16777216 = 256^3, 16777216 = 64^4. - Martin Renner, Aug 16 2017
From Jianing Song, Jul 20 2021: (Start)
Let F_q be the finite field with q elements, then in F_a(n), 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^lcm(1,2,...,n)) = Union_{n>=0} F_A178981(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^(n!). (End)
For n >= 1, the number of digits of a(n) is A317873(n). - Martin Renner, Mar 24 2024

Crossrefs

Programs

Formula

a(n) = a(n-1)^n, a(0)=2.
a(n) = A000079(A000142(n)).
Sum_{n>=1} 1/a(n) = A092874. - Amiram Eldar, Oct 27 2020

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

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)).

A236368 a(n) = 4^(n!) - 3^(n!).

Original entry on oeis.org

1, 1, 7, 3367, 281192547174175, 1766847064778382532572997586311708102647654387270579226645978663441513375
Offset: 0

Views

Author

Assoul Abdelkarim, Jan 23 2014

Keywords

Comments

a(6) has 434 digits.

Examples

			a(3) = 4^(3!) - 3^(3!) = 4^6 - 3^6 = 3367.
		

Crossrefs

Programs

Formula

a(n) = 4^(n!) - 3^(n!) = A101407(n) - A100731(n).

A260229 a(n) = floor(e^(n!)).

Original entry on oeis.org

2, 7, 403, 26489122129, 13041808783936322797338790280986488113446079415755132
Offset: 1

Views

Author

Ilya Gutkovskiy, Jul 20 2015

Keywords

Comments

The exponential growth in the number of permutations of n elements.
Next term is too big to be included.

Examples

			a(1) = floor(e^(1!)) = floor(e) = 2.
		

Crossrefs

Programs

  • Mathematica
    Table[Floor[E^n!], {n, 1, 7}]
  • PARI
    default(realprecision, 100); vector(5, n, floor(exp(n!))) \\ Michel Marcus, Aug 06 2015

Formula

a(n) = A000149(A000142(n)).
a(n) = floor(sqrt(e^A052849(n) - e^A000142(n) + sqrt(e^A052849(n) - e^A000142(n) + sqrt(e^A052849(n) - e^A000142(n) + ...)))).

A385950 Number of digits in 3^(n!).

Original entry on oeis.org

1, 1, 1, 3, 12, 58, 344, 2405, 19238, 173138, 1731378, 19045154, 228541845, 2971043978, 41594615682, 623919235225, 9982707763599, 169706031981174, 3054708575661119, 58039462937561246, 1160789258751224920, 24376574433775723304, 536284637543065912676
Offset: 0

Views

Author

Vincenzo Librandi, Jul 27 2025

Keywords

Crossrefs

Subsequence of A034888.

Programs

  • Mathematica
    Array[Floor[#! Log10@3+1]&,22]

Formula

a(n) = A055642(A100731(n)).
Showing 1-7 of 7 results.