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A109909 a(n) = number of primes of the form k*(n-k)-1. 8
0, 0, 0, 2, 2, 1, 2, 1, 4, 1, 3, 2, 3, 2, 3, 2, 4, 3, 5, 1, 10, 1, 5, 5, 4, 2, 6, 3, 5, 3, 9, 4, 11, 3, 5, 5, 5, 5, 14, 1, 6, 6, 7, 6, 11, 5, 8, 4, 15, 3, 13, 4, 10, 9, 6, 5, 11, 4, 12, 5, 13, 4, 12, 4, 6, 11, 13, 4, 12, 6, 15, 12, 9, 4, 9, 5, 10, 8, 10, 3, 28, 7, 11, 15, 6, 9, 20, 7, 20, 6, 17, 5, 23 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
COMMENTS
Conjecture: a(n) > 0 for n > 3.
Conjecture verified up to 10^9. - Mauro Fiorentini, Jul 23 2023
LINKS
CROSSREFS
Sequence in context: A262403 A343491 A326952 * A254573 A144387 A030768
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Jul 15 2005
EXTENSIONS
More terms from David Wasserman, Aug 15 2005
STATUS
approved

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Last modified March 29 01:34 EDT 2024. Contains 371264 sequences. (Running on oeis4.)