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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A181493 Numbers of the form 3*2^k which are the average of twin primes, i.e., a(n)-1 and a(n)+1 are both prime. 6
 6, 12, 192, 786432 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Sequence A181490 lists the exponents k, sequences A181491 and A181492 the corresponding twin primes. LINKS Table of n, a(n) for n=1..4. FORMULA A181493 = A014574 intersect A007283 = A181491 + 1 = A181492 - 1 = 3*2^A181490. A181493(n) = A007283(A181490(n)). A181493 = A014574 intersect A007283 = A181491 + 1 = A181492. A181493(n) = A007283(A181490(n)). MATHEMATICA Select[3 2^Range[500], PrimeQ[#-1]&&PrimeQ[#+1]&] (* Harvey P. Dale, Jan 18 2011 *) PROG (PARI) for( k=1, 999, ispseudoprime(3<

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

Last modified September 19 02:20 EDT 2024. Contains 376003 sequences. (Running on oeis4.)