OFFSET
1,1
LINKS
Jianing Song, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = 2*A348423(n) - 3.
EXAMPLE
47 is a term since it is a prime congruent to 3 modulo 4 and (47+3)/2 = 25 is composite.
MATHEMATICA
Select[4*Range[0, 300] + 3, PrimeQ[#] && ! PrimeQ[(# + 3)/2] &] (* Amiram Eldar, Oct 18 2021 *)
PROG
(PARI) isA348421(n) = isprime(n) && (n%4==3) && !isprime((n+3)/2)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jianing Song, Oct 18 2021
STATUS
approved