A341252 a(n) is the least k such that there are exactly n pairs of consecutive primes (p,q) such that (2*k-q,2*k-p) are consecutive primes.

1, 4, 5, 9, 33, 12, 24, 39, 51, 30, 63, 72, 84, 45, 57, 102, 123, 60, 297, 351, 162, 120, 252, 231, 519, 150, 285, 195, 345, 105, 360, 165, 255, 483, 510, 462, 1182, 552, 210, 1158, 330, 315, 1023, 1197, 525, 570, 690, 675, 1353, 858, 750, 645, 585, 987, 1533, 420, 900, 825, 1110, 660, 630, 960

Offset

0,2

Comments

a(n) is the least k such that A341237(k) = n.

Links

Robert Israel, Table of n, a(n) for n = 0..300

Example

a(3) = 9 as there are 3 pairs (p,q) = (5,7), (7,11), (11,13) of consecutive primes such that (18-q,18-p) = (11,13), (7,11), (5,7) are pairs of consecutive primes, and 9 is the least number for which there are 3 such pairs.

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:
V:= Array(0..100): count:= 0:
for n from 1 while count < 101 do
v:= f(n);
if v <= 100 and V[v] = 0 then count:= count+1; V[v]:= n fi
od:
convert(V, list);

Crossrefs

Cf. A341237, A341238.

Sequence in context: A352509 A222543 A042221 * A041151 A279919 A041467

Adjacent sequences: A341249 A341250 A341251 * A341253 A341254 A341255

Keyword

nonn

Author

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

Status

approved