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.

A258714 Decimal expansion of Sum_{k>=0} 1/Product_{i=0..k} (2^(2^i) - 1).

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane, Jun 15 2015

Keywords

Examples

			1.3556427028548167233332627145907395523398829385994877...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[1/NProduct[1 - 1/2^(2^k), {k, 0, Infinity}, WorkingPrecision -> 120] - 3/2][[1]] (* Amiram Eldar, Feb 19 2024 *)
  • PARI
    1/prodinf(k = 0, 1 - 1/2^(2^k)) - 3/2 \\ Amiram Eldar, Feb 19 2024

Formula

From Amiram Eldar, Feb 19 2024: (Start)
Equals Sum_{n>=0} 1/A370458(n).
Equals 1/A215016 - 3/2. (End)

A258716 Decimal expansion of 3 + 2*Sum_{k>=0} 1/Product_{i=0..k} (2^(2^i) - 1).

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane, Jun 15 2015

Keywords

Examples

			5.7112854057096334466665254291814791046797658771989754...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[2/NProduct[1 - 1/2^(2^k), {k, 0, Infinity}, WorkingPrecision -> 120]][[1]] (* Amiram Eldar, Feb 19 2024 *)
  • PARI
    2/prodinf(k = 0, 1 - 1/2^(2^k)) \\ Amiram Eldar, Feb 19 2024

Formula

Equals 3 + A258715.
From Amiram Eldar, Feb 19 2024: (Start)
Equals 2 * A258714 + 3.
Equals 2/A215016. (End)

A370458 Partial products of A051179.

Original entry on oeis.org

1, 3, 45, 11475, 752014125, 3229876072253041875, 59580697294650083747194059426068878125, 20274260698223485458204828871028994444941136941453077244297515184669623921875
Offset: 0

Views

Author

Amiram Eldar, Feb 19 2024

Keywords

Crossrefs

Programs

  • Mathematica
    FoldList[Times, Table[2^(2^n) - 1, {n, 0, 7}]]
  • PARI
    lista(nmax) = {my(v = 1); for(i = 0, nmax, v *= (2^(2^i) - 1); print1(v, ", "));}
    
  • Python
    from math import prod
    def A370458(n): return prod((1<<(1<Chai Wah Wu, Feb 19 2024

Formula

a(n) = Product_{k=0..n} A051179(k).
Sum_{n>=0} 1/a(n) = A258714 = 1/A215016 - 3/2 = 1.355642702854... (Knuth, 2013).
Showing 1-3 of 3 results.