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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. 3
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 (list; graph; refs; listen; history; text; internal format)
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.

Sequence in context: A144219 A144027 A019591 * A091967 A031135 A037181

Adjacent sequences:  A341234 A341235 A341236 * A341238 A341239 A341240

KEYWORD

nonn

AUTHOR

J. M. Bergot and Robert Israel, Feb 07 2021

STATUS

approved

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Last modified December 3 20:35 EST 2021. Contains 349468 sequences. (Running on oeis4.)