A152050 Smallest lower twin prime tp such that p + tp + 1 is prime. p ranges over the prime numbers.

3, 5, 3, 5, 3, 5, 3, 5, 11, 5, 3, 5, 3, 5, 5, 11, 5, 3, 11, 5, 3, 5, 11, 3, 5, 3, 5, 3, 17, 3, 5, 11, 11, 17, 5, 5, 3, 5, 5, 11, 11, 5, 3, 29, 11, 11, 3, 5, 3, 5, 11, 29, 5, 5, 5, 11, 5, 3, 11, 29, 17, 3, 5, 3, 29, 5, 11, 5, 3, 5, 29, 5, 5, 3, 5, 11, 3, 17, 11, 11, 11, 11, 5, 3, 5, 11, 3, 5, 3, 11

Offset

1,1

Comments

Conjecture: For all primes p <= n there is always a lower twin prime L less than n such that p+L+1 is prime.

Links

Table of n, a(n) for n=1..90.

Example

29 is the 9th odd prime. 29+3+1, 29+5+1 are not prime. 29+11+1 is prime, so a(9) = 11 the smallest lower twin prime satisfying the definition for prime 29.

Prog

(PARI) g(n) = ct=0; for(x=2, n, p1=prime(x); for(y=1, n, p2=twinl(y); z=p1+p2+1;
if(isprime(z), ct++; print1(p2", "); break))); ct

Crossrefs

Sequence in context: A214287 A010703 A107489 * A103506 A094929 A096634

Adjacent sequences: A152047 A152048 A152049 * A152051 A152052 A152053

Keyword

nonn

Author

Cino Hilliard, Nov 21 2008

Status

approved