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A067432
Number of ways to represent the n-th prime in form p*q+p+q, where p and q are primes (see A066938).
5
0, 0, 0, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 2, 1, 1, 0, 0, 3, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 2, 0, 2, 0, 3, 0, 0, 0, 0, 0, 1, 0, 0, 4, 0, 3, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 3, 0, 0, 0, 0, 2, 0, 4, 0, 1, 1, 1, 0, 0, 0
OFFSET
1,9
COMMENTS
a(A049084(A066938(n))) > 0; a(A049084(A198273(n))) = 0; a(A049084(A198277(n))) = n and a(A049084(m)) <> n for m < A198277(n). [Reinhard Zumkeller, Oct 23 2011]
a(n) < A072670(n).
LINKS
EXAMPLE
a(15) = 2 as A000040(15) = 47 = 3*11+3+11 = 5*7+5+7.
PROG
(Haskell)
a067432 n = length [p | let prime_n = a000040 n,
p <- takeWhile (< a000196 prime_n) a000040_list,
let (q, m) = divMod (prime_n - p) (p + 1),
m == 0, a010051 q == 1]
a067432_list = map a067432 [1..]
-- Reinhard Zumkeller, Oct 23 2011
CROSSREFS
Sequence in context: A035169 A340728 A275851 * A364011 A192174 A262202
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Feb 15 2002
STATUS
approved