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.

A081573 Decimal expansion of Sum_(1/(2^q-1)) with the summation extending over all pairs of integers gcd(p,q) = 1, 0 < p/q < e = 2.718... .

Original entry on oeis.org

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

Views

Author

Benoit Cloitre, Apr 21 2003

Keywords

Examples

			4.866141732...
		

Crossrefs

Cf. A001113 (e).

Programs

  • Mathematica
    With[{digmax = 120}, RealDigits[Sum[1/2^Floor[k/E], {k, 1, 20*digmax}], 10, digmax][[1]]] (* Amiram Eldar, May 25 2023 *)

Formula

Equals Sum_{k>=1} (1/2)^floor(k/e) = Sum_{k>=1} 1/2^A032634(k).

Extensions

Data corrected by Amiram Eldar, May 25 2023