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A342993 Numbers of the form prime(i-1)+prime(i+1) that are the average of a twin prime pair. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
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
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Apr 01 2021
STATUS
approved

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Last modified May 21 19:35 EDT 2024. Contains 372738 sequences. (Running on oeis4.)