OFFSET
1,1
COMMENTS
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
MATHEMATICA
sgp2Q[p_]:=Module[{s=2p+1}, AllTrue[{s, p 10^IntegerLength[s]+s}, PrimeQ]]; Select[ Prime[ Range[ 1500]], sgp2Q] (* Harvey P. Dale, Jul 11 2023 *)
PROG
(PARI) forprime(p=1, 19999, isprime(2*p+1) & isprime(eval(Str(p, 2*p+1))) & print1(p", "))
CROSSREFS
KEYWORD
base,nonn
AUTHOR
M. F. Hasler, Nov 25 2009
STATUS
approved