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A098014 A098013/2. 0
2, 2, 2, 3, 3, 2, 2, 3, 3, 3, 2, 3, 2, 3, 2, 2, 2, 7, 2, 3, 5, 3, 3, 2, 3, 3, 5, 2, 2, 2, 3, 5, 3, 3, 3, 3, 2, 5, 7, 2, 2, 7, 3, 5, 2, 3, 3, 3, 2, 3, 2, 5, 5, 3, 2, 3, 2, 2, 2, 2, 3, 3, 5, 3, 3, 3, 5, 3, 3, 3, 3, 2, 5, 2, 3, 3, 2, 3, 5, 5, 3, 3, 2, 3, 2, 2, 7, 5, 5, 2, 5, 7, 2, 2, 7, 2, 2, 2, 5, 2, 3, 3, 7, 2, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Half the difference between consecutive primes is prime.

(1/2)(29 - 23) = 3, the 4th entry in the table.

LINKS

Table of n, a(n) for n=1..105.

MATHEMATICA

Select[Differences[Prime[Range[250]]]/2, PrimeQ] (* Harvey P. Dale, Dec 20 2012 *)

PROG

(PARI) f(n) = for(x=1, n, y=prime(x+1)-prime(x); if(isprime(y\2), print1(y\2", ")))

(MAGMA) [ a: n in [1..2500] | IsPrime(a) where a is ((NthPrime(n+1)-NthPrime(n)) div 2 )]; // Vincenzo Librandi, Apr 19 2011

CROSSREFS

Sequence in context: A124064 A317369 A096916 * A059957 A165924 A212628

Adjacent sequences:  A098011 A098012 A098013 * A098015 A098016 A098017

KEYWORD

easy,nonn

AUTHOR

Cino Hilliard, Sep 09 2004

STATUS

approved

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Last modified October 20 22:05 EDT 2019. Contains 328291 sequences. (Running on oeis4.)