login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A172411 Numbers n such that 2^n+9 and 2^n+27 are prime. 0
1, 2, 5, 10 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

No further terms between 10 and 5000. - R. J. Mathar, Feb 07 2010

No further terms to 100000. Expected number of remaining terms: (zeta(2) - 1 - 1/4 - ... - 1/100000^2)/log^2 2 ~= 0.00002. - Charles R Greathouse IV, Mar 25 2010

LINKS

Table of n, a(n) for n=1..4.

FORMULA

A057196 INTERSECT A157007 - R. J. Mathar, Feb 07 2010

EXAMPLE

a(1)=1 because 2^1+3^2=11 and 2^1+3^3=29 are prime.

MATHEMATICA

Select[Range[10], AllTrue[2^#+{9, 27}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, May 28 2016 *)

PROG

(PARI) is(n)=isprime(2^n+9) && isprime(2^n+27) \\ Charles R Greathouse IV, Sep 06 2016

CROSSREFS

Sequence in context: A188948 A334295 A083460 * A264784 A306679 A125974

Adjacent sequences:  A172408 A172409 A172410 * A172412 A172413 A172414

KEYWORD

nonn,less

AUTHOR

Juri-Stepan Gerasimov, Feb 02 2010

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 30 02:06 EDT 2022. Contains 354913 sequences. (Running on oeis4.)