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A152050 Smallest lower twin prime tp such that p + tp + 1 is prime. p ranges over the prime numbers. +0
1
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 (list; graph; listen)
OFFSET

1,1

COMMENT

Conjecture: For all primes p <= n there is always a lower twin prime L less

than n such that p+L+1 is prime.

EXAMPLE

29 is the 9-th 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.

PROGRAM

(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: A077973 A010703 A107489 this_sequence A103506 A094929 A096634

Adjacent sequences: A152047 A152048 A152049 this_sequence A152051 A152052 A152053

KEYWORD

nonn

AUTHOR

Cino Hilliard (hillcino368(AT)hotmail.com), Nov 21 2008

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Last modified December 6 22:55 EST 2009. Contains 170429 sequences.


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