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A062301
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Number of ways writing n-th prime as a sum of two primes.
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8
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0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1
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OFFSET
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1,1
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COMMENTS
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LINKS
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MAPLE
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a:= n-> `if`(isprime(ithprime(n)-2), 1, 0):
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MATHEMATICA
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Table[Sum[(PrimePi[Prime[n] - i] - PrimePi[Prime[n] - i - 1]) (PrimePi[i] - PrimePi[i - 1]), {i, Floor[Prime[n]/2]}], {n, 100}] (* Wesley Ivan Hurt, Apr 04 2018 *)
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PROG
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(GAP) P:=Filtered([1..1000], IsPrime);; a:=List(List(List(P, i -> Partitions(i, 2)), k -> Filtered(k, i -> IsPrime(i[1]) and IsPrime(i[2]))), Length); # Muniru A Asiru, Apr 05 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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