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

1,1

Links

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

Example

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.

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;

Prog

(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

Crossrefs

Intersection of A048448 and A014574.

Cf. A000040.

Sequence in context: A173728 A173547 A173727 * A039498 A063357 A240247

Adjacent sequences: A342990 A342991 A342992 * A342994 A342995 A342996

Keyword

nonn

Author

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

Status

approved