login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A128193 First differences of values of n for Cullen primes in A005849. 1
140, 4572, 1082, 816, 11885, 13796, 177, 27187, 31169, 171594, 98856, 120624, 872929, 4973720, 351333 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Carlos Rivera's Problem 50 is devoted to this topic. If we pair differences according to magnitude, we first obtain 177-140=37 a prime. This raises the question as to whether there are other such prime values.

LINKS

Table of n, a(n) for n=1..15.

Carlos Rivera, Problem 50. Is there a Cullen prime Cn with n prime ?, The Prime Puzzles and Problems Connection.

FORMULA

a(n) = A005849(n+1) - A005849(n). - Michel Marcus, Sep 27 2020

EXAMPLE

a(1)=140 because the first pair of n are 1 and 141. 141-1=140.

CROSSREFS

Cf. A005849, A128194.

Sequence in context: A255775 A199831 A264310 * A061607 A223349 A282613

Adjacent sequences:  A128190 A128191 A128192 * A128194 A128195 A128196

KEYWORD

easy,nonn,more

AUTHOR

Enoch Haga, Feb 18 2007

EXTENSIONS

Offset 1 from Michel Marcus, Sep 27 2020

a(14)-a(15) added by Florian Baur, Sep 27 2020

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 18 23:37 EDT 2021. Contains 344008 sequences. (Running on oeis4.)