OFFSET
1,2
COMMENTS
a(n) is odd for all n. For n > 2, the last digit of a(n) is either 5 or 7 because for n == 1, 3, 9 mod 10, either n+2 == 5 (mod 10) or n^2+4 == 5 (mod 10). Thus if m>1 is a term, then m+2 is in A045378. - Chai Wah Wu, Sep 06 2020
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
1 + 2 = 3 and 1 + 4 = 5 are primes,
3 + 2 = 5 and 9 + 4 = 13 are primes,
5 + 2 = 7 and 25 + 4 = 29 are primes.
MAPLE
filter:= n -> isprime(n+2) and isprime(n^2+4):
select(filter, [seq(i, i=1..2000, 2)]); # Robert Israel, Nov 11 2023
PROG
(PARI) {a=2; forstep(n=1, 2000, 2, if(isprime(n+a)&&isprime(n^2+a^2), print1(n", ")))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Dec 19 2012
STATUS
approved