This site is supported by donations to The OEIS Foundation.

Template:Sequence of the Day for March 11

From OeisWiki
Jump to: navigation, search


Intended for: March 11, 2013

Timetable

  • First draft entered by Alonso del Arte on March 10, 2011
  • Draft reviewed by Daniel Forgues on March 11, 2016
  • Draft to be approved by February 11, 2013

Yesterday's SOTD * Tomorrow's SOTD

The line below marks the end of the <noinclude> ... </noinclude> section.



A055265: Smallest positive integer not already in the sequence for which
a (n) + a (n  −  1)
is prime, with
a (1) = 1
.
{ 1, 2, 3, 4, 7, 6, 5, 8, 9, 10, 13, 16, 15, 14, 17, 12, 11, ... }

Dmitry Kamenetsky wonders if every positive integer occurs, or, in other words, if this sequence is a permutation of the positive integers. According to Robert Wilson, “The answer is almost certainly yes, on probabilistic grounds.” The sequence is infinite by definition, so it is at least a permutation of an infinite subset of the positive integers.