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A231483
Smallest k > A082467(n) such that n-k and n+k are both prime.
1
9, 8, 15, 18, 7, 12, 15, 10, 15, 18, 7, 28, 15, 10, 27, 12, 7, 24, 15, 8, 21, 18, 5, 30, 15, 8, 27, 24, 11, 18, 9, 10, 15, 30, 13, 18, 15, 10, 21, 30, 7, 42, 21, 10, 33, 18, 7, 30, 21, 10, 9, 18, 11, 30, 27, 8, 33, 24, 11, 48, 21, 8, 21, 30
OFFSET
20,1
COMMENTS
Starting at n=20 just because there are some n<20 without solution like for n=19, for the least k (A082467) it start at 4 as no solution for n<4.
PROG
(PARI) a(n) = {k=1; while(isprime(n-k)*isprime(n+k) == 0, k++); k++; while(isprime(n-k)*isprime(n+k) == 0, k++); k; } \\ Michel Marcus, Nov 10 2013
CROSSREFS
Cf. A082467.
Sequence in context: A272962 A137392 A307639 * A309656 A370882 A363327
KEYWORD
nonn
AUTHOR
Pierre CAMI, Nov 09 2013
STATUS
approved