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 1-3 of 3 results.

A300753 Decimal expansion of the constant B such that ceiling(B^(3^k)) = A118910(k) is prime for all k >= 0.

Original entry on oeis.org

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

Views

Author

Amiram Eldar, Jun 19 2018

Keywords

Comments

Tóth calculated the first 5500 decimal digits of this constant. The first 600 digits are presented in his paper.

Examples

			1.24055470525201424067469515337900345212353396725255...
		

Crossrefs

Formula

Lim_{n->oo} (A118910(n) - 1)^(3^(-n)).

A051254 Mills primes.

Original entry on oeis.org

2, 11, 1361, 2521008887, 16022236204009818131831320183, 4113101149215104800030529537915953170486139623539759933135949994882770404074832568499
Offset: 1

Views

Author

Keywords

Comments

Mills showed that there is a number A > 1 but not an integer, such that floor( A^(3^n) ) is a prime for all n = 1, 2, 3, ... A is approximately 1.306377883863... (see A051021).
a(1) = 2 and (for n > 1) a(n) is least prime > a(n-1)^3. - Jonathan Vos Post, May 05 2006, corrected by M. F. Hasler, Sep 11 2024
The name refers to the American mathematician William Harold Mills (1921-2007). - Amiram Eldar, Jun 23 2021

Examples

			a(3) = 1361 = 11^3 + 30 = a(2)^3 + 30 and there is no smaller k such that a(2)^3 + k is prime. - _Jonathan Vos Post_, May 05 2006
		

References

  • Tom M. Apostol, Introduction to Analytic Number Theory, Springer-Verlag, 1976, page 8.
  • Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 2.13, p. 130.
  • Paulo Ribenboim, The Little Book of Bigger Primes, Springer-Verlag NY 2004. See p. 137.

Crossrefs

Cf. A224845 (integer lengths of Mills primes).
Cf. A108739 (sequence of offsets b_n associated with Mills primes).
Cf. A051021 (decimal expansion of Mills constant).

Programs

  • Maple
    floor(A^(3^n), n=1..10); # A is Mills's constant: 1.306377883863080690468614492602605712916784585156713644368053759966434.. (A051021).
  • Mathematica
    p = 1; Table[p = NextPrime[p^3], {6}] (* T. D. Noe, Sep 24 2008 *)
    NestList[NextPrime[#^3] &, 2, 5] (* Harvey P. Dale, Feb 28 2012 *)
  • PARI
    a(n)=if(n==1, 2, nextprime(a(n-1)^3)) \\ Charles R Greathouse IV, Jun 23 2017
    
  • PARI
    apply( {A051254(n, p=2)=while(n--, p=nextprime(p^3));p}, [1..6]) \\ M. F. Hasler, Sep 11 2024

Formula

a(1) = 2; a(n) is least prime > a(n-1)^3. - Jonathan Vos Post, May 05 2006

Extensions

Edited by N. J. A. Sloane, May 05 2007

A118912 a(1) = 2; a(n) is greatest prime < a(n-1)^4.

Original entry on oeis.org

2, 13, 28559, 665230244078823349, 195833931687186822327230545227550596864953022841534058316595001440791433
Offset: 1

Views

Author

Jonathan Vos Post, May 05 2006

Keywords

Comments

Exponent-4 analog of A059785 a(n+1)=prevprime(a(n)^2), with exponent 3 being A118910 a(1) = 2; a(n) is greatest prime < a(n-1)^3.

Examples

			a(1) = 2, by definition.
a(2) = 13 = 2^4 - 3.
a(3) = 28559 = 13^4 - 2.
a(4) = 665230244078823349 = 28559^4 - 12.
a(5) = 195833931687186822327230545227550596864953022841534058316595001440791433 = 665230244078823349^4 - 168.
a(6) is too large to include.
		

Crossrefs

Programs

  • Mathematica
    NestList[NextPrime[#^4,-1]&,2,5] (* Harvey P. Dale, Feb 18 2025 *)

Formula

a(1) = 2; a(n) is greatest prime < a(n-1)^4.
Showing 1-3 of 3 results.