OFFSET
1,1
FORMULA
a(n) = 2*A163656(n).
MATHEMATICA
Total /@ Partition[#, 2, 1] &@ Select[Prime@ Range@ 105, Total@ Boole@ Map[PrimeQ, # + 2 {-1, 1}] > 0 &] (* Michael De Vlieger, Jan 11 2017 *)
PROG
(PARI) {
t=4;
forstep(n=6, 1000, 6,
if(isprime(n-1)&&isprime(n+1),
k=2*n; print1((k+t)/2", ")
; print1(k", "); t=k
)
)
}
CROSSREFS
KEYWORD
nonn
AUTHOR
Dimitris Valianatos, Jan 11 2017
STATUS
approved