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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A054273 Number of primes p in the interval prime(n+1) <= p < prime(n+1)^2 such that A002110(n)+p is prime. 0

%I

%S 2,6,10,19,23,29,25,38,42,35,56,54,45,60,67,84,66,76,94,98,95,92,108,

%T 108,107,129,127,128,127,152,160,152,145,173,153,156,183,214,208,212,

%U 201,220,220,219,222,248,255,241,252,265,265,252,280,276,291,292

%N Number of primes p in the interval prime(n+1) <= p < prime(n+1)^2 such that A002110(n)+p is prime.

%e n=3, prime(4)=7, prime(4)^2=49; 3rd primorial number = 30; in interval [7,49] 12 primes p occur of which 10 are such that 30+p is prime, namely 30+{7,11,13,17,23,29,31,37,41,43} = {37,41,...,73}, "post-primorial primes", while two primes 19 and 47 yield 49, 77 which are composites. So a(3)=10.

%Y Cf. A000879, A001248, A000040, A005235, A002110.

%K nonn

%O 1,1

%A _Labos Elemer_, May 05 2000

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 12 19:19 EST 2018. Contains 317116 sequences. (Running on oeis4.)