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A248597 a(n) = A248595(n) - prime(n)*A248596(n). 1
1, 1, 1, 2, 1, 2, 2, 2, 1, 1, 2, 2, 1, 2, 4, 1, 2, 2, 2, 4, 2, 2, 1, 1, 2, 4, 2, 2, 2, 1, 2, 1, 4, 2, 2, 2, 2, 2, 2, 1, 1, 2, 1, 2, 2, 2, 4, 2, 2, 4, 1, 1, 6, 1, 2, 4, 2, 4, 2, 1, 6, 1, 4, 4, 2, 2, 2, 2, 4, 2, 2, 1, 2, 2, 4, 2, 4, 2, 10, 2, 1, 6, 1, 2, 2, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

If a(n)=1 then prime(n) is a Sophie Germain prime.

Except for Sophie Germain primes a(n) is always even.

Conjecture: all even numbers are present many times in A248597(n) and any even number may be written in many ways as the difference between a prime Q and a product of two primes P*R.

LINKS

Pierre CAMI, Table of n, a(n) for n = 1..10000

CROSSREFS

Cf. A005384 (Sophie Germain primes), A248595, A248596.

Sequence in context: A105307 A281012 A304943 * A082071 A082065 A082070

Adjacent sequences:  A248594 A248595 A248596 * A248598 A248599 A248600

KEYWORD

nonn

AUTHOR

Pierre CAMI, Oct 09 2014

STATUS

approved

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Last modified December 8 14:38 EST 2019. Contains 329865 sequences. (Running on oeis4.)