login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A014741 Numbers n such that n divides 2^(n+1) - 2. 7
1, 2, 6, 18, 42, 54, 126, 162, 294, 342, 378, 486, 882, 1026, 1134, 1314, 1458, 1806, 2058, 2394, 2646, 3078, 3402, 3942, 4374, 5334, 5418, 6174, 6498, 7182, 7938, 9198, 9234, 10206, 11826, 12642, 13122, 14154, 14406, 16002, 16254 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also, numbers n such that n divides Eulerian number A000295(n+1) = 2^(n+1) - n - 2.

Also, numbers n such that n divides A086787(n) = Sum[ i^j, {i, 1, n}, {j, 1, n}].

All terms greater than 1 are even; for a proof, see comment in A036236. - Max Alekseyev, Feb 03 2012

If k>1 is a term, then 3*k is also a term. - Alexander Adamchuk, Nov 03 2006

Prime numbers of the form a(m)+1 are given by A069051. - Max Alekseyev, Nov 14 2012

LINKS

Table of n, a(n) for n=1..41.

FORMULA

For n>1, a(n) = 2*A014945(n-1). - Max Alekseyev, Nov 14 2012

MATHEMATICA

Join[{1, 2}, Select[Range[17000], PowerMod[2, #+1, #]==2&]] (* Harvey P. Dale, Feb 11 2015 *)

PROG

(PARI) is(n)=Mod(2, n)^(n+1)==2 \\ Charles R Greathouse IV, Nov 03 2016

CROSSREFS

Cf. A000295, A086787, A015919, A006517.

Sequence in context: A064842 A302647 A101695 * A016059 A291519 A027556

Adjacent sequences:  A014738 A014739 A014740 * A014742 A014743 A014744

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Olivier Gérard

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 14 03:52 EST 2018. Contains 317159 sequences. (Running on oeis4.)