A342993 Numbers of the form prime(i-1)+prime(i+1) that are the average of a twin prime pair.

72, 150, 180, 270, 1032, 1062, 1452, 1608, 2028, 2082, 2130, 2592, 2790, 3120, 3258, 3300, 3360, 3930, 4020, 4272, 4650, 4722, 4788, 4932, 5442, 5880, 6702, 7128, 7332, 7878, 8388, 8430, 8862, 9240, 9342, 9678, 10008, 10140, 10272, 10890, 11490, 11940, 12072, 12162, 12918, 13002, 13218, 13932

Offset: 1

Author

J. M. Bergot and Robert Israel, Apr 01 2021

Keywords

• nonn

Examples

			a(3) = 180 is a term because 180 = 83 + 97 = prime(23)+prime(25) and (180-1 = 179, 180+1 = 181) is a twin prime pair.
		

Links

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

Crossrefs

Intersection of A048448 and A014574.

Cf. A000040.

Programs

Maple

count:= 0: R:= NULL:
for i from 1 while count < 100 do
  x:= ithprime(i)+ithprime(i+2);
  if isprime(x-1) and isprime(x+1) then R:= R, x; fi
od:
R;

PARI

lista(nn) = {for (n=2, nn, my(x=prime(n)+prime(n+2)); if (isprime(x-1) && isprime(x+1), print1(n, ", ")););} \\ Michel Marcus, Apr 02 2021