OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
C. K. Caldwell, Twin primes
FORMULA
a(n) = A173165(n)/3. - M. F. Hasler, Oct 30 2023
EXAMPLE
E.g. n=44 -> (6*44)^2 = 69696 = 34847 + 34849 (twin prime pair).
MAPLE
isa := n -> isprime(n) and isprime(n+2) and issqr(2*n+2):
select(isa, [$4..1000000]): map(n -> sqrt(2*n+2)/6, %); # Peter Luschny, Jan 05 2020
MATHEMATICA
Select[Sqrt[Plus@@@Select[Partition[Prime[Range[4*10^5]], 2, 1], Differences[#]=={2} &]/36], IntegerQ] (* Jayanta Basu, May 26 2013 *)
PROG
(PARI) is(n)=isprime(18*n^2-1)&&isprime(18*n^2+1) \\ M. F. Hasler, Oct 30 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Jud McCranie, Dec 30 2000
STATUS
approved
