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A341237
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a(k) is the number of pairs of consecutive primes (p,q) such that (2*k-q,2*k-p) is also a pair of consecutive primes.
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3
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0, 0, 0, 1, 2, 1, 0, 2, 3, 0, 2, 5, 0, 0, 5, 0, 2, 5, 0, 0, 3, 0, 2, 6, 0, 1, 6, 0, 0, 9, 0, 2, 4, 1, 0, 4, 0, 4, 7, 0, 2, 9, 0, 0, 13, 0, 0, 2, 2, 1, 8, 0, 4, 6, 2, 5, 14, 0, 0, 17, 0, 0, 10, 1, 0, 8, 0, 2, 7, 2, 4, 11, 0, 0, 14, 1, 2, 6, 0, 2, 7, 0, 0, 12, 0, 1, 8, 0, 0, 14, 0, 4, 9, 2, 2, 6, 2
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OFFSET
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1,5
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LINKS
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EXAMPLE
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a(9) = 3 because (5,7), (7,11) and (11,13) are pairs of consecutive primes (p,q) with (18-q,18-p) = (11,13), (7,11) and (5,7) also consecutive primes.
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MAPLE
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f:= proc(n) local p, q, count;
q:= 2: count:= 0:
while q < 2*n -2 do
p:= q; q:= nextprime(q);
if isprime(2*n-p) and prevprime(2*n-p)=2*n-q then count:= count+1 fi;
od;
count
end proc:
map(f, [$1..100]);
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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