OFFSET
1,1
LINKS
T. D. Noe, Table of n, a(n) for n = 1..10000
EXAMPLE
MATHEMATICA
sumProd[p_, q_, r_]:=p*q+p*r+q*r; pqrPrimes[nn_] := Module[{p=Prime[Range[PrimePi[(nn-6)/5]+1]], i, j, k, n}, Union[Reap[i=0; While[i++; sumProd[p[[i]], p[[i+1]], p[[i+2]]] <= nn, j=i; While[j++; sumProd[p[[i]], p[[j]], p[[j+1]]] <= nn, k=j; While[k++; n=sumProd[p[[i]], p[[j]], p[[k]]]; n <= nn, If[PrimeQ[n], Sow[n]]]]]][[2, 1]]]]; pqrPrimes[1000] (* T. D. Noe, Apr 27 2011 *)
nn=100; Take[Select[Union[Total[Times@@@Subsets[#, {2}]]&/@Subsets[ Prime[ Range[ nn]], {3}]], PrimeQ], nn] (* Harvey P. Dale, Jan 08 2013 *)
PROG
(PARI) list(lim)=my(v=List()); forprime(r=5, (lim-6)\5, forprime(q=3, min((lim-2*r)\(r+2), r-2), my(S=q+r, P=q*r); forprime(p=2, min((lim-P)\S, q-1), isprime(p*S+P) && listput(v, p*S+P)))); Set(v) \\ Charles R Greathouse IV, Feb 26 2014
(PARI) is(n)=forprime(r=(sqrtint(3*n-3)+5)\3, (n-6)\5, forprime(q= sqrtint(r^2+n)-r+1, min((n-2*r)\(r+2), r-2), if((n-q*r)%(q+r)==0 && isprime((n-q*r)/(q+r)), return(isprime(n))))); 0 \\ Charles R Greathouse IV, Feb 26 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Aug 07 2003
EXTENSIONS
Corrected by T. D. Noe, Apr 27 2011
STATUS
approved