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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A087865 Prime numbers of the form primepi(3^m), for some integer m. 1
 2, 53, 16097, 120739, 334349, 18703411700669 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS These are the prime terms in A055729. LINKS Table of n, a(n) for n=1..6. MATHEMATICA Select[ Table[ PrimePi[ 3^n], {n, 0, 49}], PrimeQ@# &] (* Robert G. Wilson v, Feb 25 2010 *) PROG (PARI) primeslessxn2(n, p) = /*primes < p^n if prime */ { sr=0; for(x=0, n, y=primepi(p^x); if(y<>0, sr+=1.0/y); if(isprime(y), print1(y", ")); ); print(); print(sr) } (Python) from itertools import islice from sympy import isprime, primepi def A087865_gen(): # generator of terms k = 1 while True: k *= 3 if isprime(p:=primepi(k)): yield p A087865_list = list(islice(A087865_gen(), 5)) # Chai Wah Wu, Jun 06 2024 CROSSREFS Cf. A055729 (number of primes <= 3^n). Sequence in context: A176946 A265443 A234603 * A278843 A083471 A078691 Adjacent sequences: A087862 A087863 A087864 * A087866 A087867 A087868 KEYWORD nonn,more,hard AUTHOR Cino Hilliard, Oct 27 2003 EXTENSIONS a(6) added by David Baugh, Mar 17 2015 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.

Last modified August 11 15:24 EDT 2024. Contains 375073 sequences. (Running on oeis4.)