A341237 - OEIS

A341237

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.

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

1,5

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

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.

MAPLE

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]);

CROSSREFS

Cf. A002372.