A336374 Numbers k such that gcd(k, prime(k) + prime(k+2)) = 1.

1, 3, 5, 7, 11, 13, 15, 17, 19, 23, 27, 29, 31, 35, 37, 39, 41, 43, 47, 49, 53, 55, 59, 61, 63, 65, 67, 69, 71, 73, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 107, 109, 113, 115, 119, 121, 127, 129, 131, 135, 137, 139, 141, 143, 147, 149, 151

Offset

1,2

Comments

This sequence and A336374 partition the positive integers.

Links

Table of n, a(n) for n=1..61.

Example

In the following table, p(k) = A000040(k) = prime(k).
  k    p(k)   p(k)+p(k+2)   gcd
  1     2         7          1
  2     3        10          2
  3     5        16          1
  4     7        20          4
  5    11        28          1
  6    13        32          2
1 and 3 are in this sequence; 2 and 4 are in A336375; 2 and 5 are in A336376; 3 and 7 are in A336377.

Mathematica

p[n_] := Prime[n];
u = Select[Range[200], GCD[#, p[#] + p[# + 2]] == 1 &]  (* A336374 *)
v = Select[Range[200], GCD[#, p[#] + p[# + 2]] > 1 &]   (* A336375 *)
Prime[u]  (* A336376 *)
Prime[v]  (* A336377 *)

Crossrefs

Cf. A000040, A336366, A336375, A336376, A336377.

Sequence in context: A210719 A353685 A322840 * A346669 A187929 A272872

Adjacent sequences: A336371 A336372 A336373 * A336375 A336376 A336377

Keyword

nonn

Author

Clark Kimberling, Oct 06 2020

Status

approved