OFFSET
1,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
EXAMPLE
26 is in the sequence because 26 = 2*13, the next semiprime is 33 = 3*11, and 26+33 = 59 is prime.
MATHEMATICA
L = Select[Range@1660, PrimeOmega@# == 2 &]; Pick[Most@L, PrimeQ[Plus @@@ Partition[L, 2, 1]]] (* Giovanni Resta, Apr 25 2016 *)
PROG
(PARI) proxsem(n)=my(p=n, s, r); while(s==0, p++; if(bigomega(p)==2, s=1; r=p)); p
for(i=1, 2000, if(bigomega(i)==2, a=proxsem(i)+i; if(isprime(a), print1(i, ", "))))
(PARI) list(lim)=my(v=List(), u=v); lim\=1; while(bigomega(lim++)!=2, ); forprime(p=2, lim\2, forprime(q=2, lim\p, listput(v, p*q))); v=Set(v); for(i=1, #v-1, if(isprime(v[i+1]+v[i]), listput(u, v[i]))); Set(u) \\ Charles R Greathouse IV, Apr 29 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Antonio Roldán, Apr 25 2016
STATUS
approved