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A066868
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Least natural number k such that n + sum{i=1,...,k} Safe_Prime[i] is prime, if such k exists; = 0 otherwise.
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0
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2, 1, 10, 5, 2, 1, 2, 1, 12, 5, 2, 1, 4, 1, 4, 5, 2, 1, 2, 3, 4, 7, 12, 1, 2, 1, 4, 7, 2, 3, 2, 1, 4, 5, 2, 1, 4, 1, 6, 17, 2, 1, 4, 3, 6, 5, 2, 1, 2, 3, 4, 11, 12, 1, 2, 1, 4, 5, 2, 3, 2, 1, 4, 5, 14, 1, 2, 1, 10, 5, 2, 7, 10, 1, 6, 7, 2, 1, 8, 3, 4, 7, 26, 1, 2, 3, 6, 5, 2, 3, 2, 1, 4, 11, 2, 1, 2, 1, 6
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| Safe_Prime[i] denotes the i-th safe prime (A005385). Conjecture: a(n) is nonzero for all n, so every n can be represented as the difference between a prime and a partial sum of the safe primes series. See A066753 for a similar conjecture.
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EXAMPLE
| 4 + (5 + 7 + 11 + 23 + 47) = 97, a prime and 5 consecutive safe primes, starting from the first safe prime 5, are needed to achieve this. Hence a(4) = 5.
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CROSSREFS
| Cf. A005385, A066753.
Sequence in context: A121334 A126450 A112333 * A193900 A143172 A004747
Adjacent sequences: A066865 A066866 A066867 * A066869 A066870 A066871
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KEYWORD
| nonn
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AUTHOR
| Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Jan 21 2002
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