A054273 Number of primes p in the interval prime(n+1) <= p < prime(n+1)^2 such that A002110(n)+p is prime.

2, 6, 10, 19, 23, 29, 25, 38, 42, 35, 56, 54, 45, 60, 67, 84, 66, 76, 94, 98, 95, 92, 108, 108, 107, 129, 127, 128, 127, 152, 160, 152, 145, 173, 153, 156, 183, 214, 208, 212, 201, 220, 220, 219, 222, 248, 255, 241, 252, 265, 265, 252, 280, 276, 291, 292

Offset

1,1

Links

Table of n, a(n) for n=1..56.

Example

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.

Crossrefs

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

Sequence in context: A095358 A084481 A006553 * A127567 A360420 A169643

Adjacent sequences: A054270 A054271 A054272 * A054274 A054275 A054276

Keyword

nonn

Author

Labos Elemer, May 05 2000

Status

approved