OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
a(2)=53 because it is prime and 52=2^2*13, 54=2*3^3 and 2+2+13=17 and 2+3+3+3=11.
MATHEMATICA
primeSopfQ[n_] := PrimeQ[Plus @@ Times @@@ FactorInteger[n]]; seqQ[n_] := PrimeQ[n] && AllTrue[{n - 1, n + 1}, primeSopfQ]; Select[Range[10^4], seqQ] (* Amiram Eldar, Dec 14 2019 *)
PROG
(Magma) [ n : n in [3..9100] | IsPrime(n) and IsPrime(&+[ k[1]*k[2] : k in Factorization(n-1)]) and IsPrime(&+[ k[1]*k[2] : k in Factorization(n+1)]) ]; /* Klaus Brockhaus, Mar 24 2007 */
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jason Earls, Jul 29 2003
EXTENSIONS
Checked by Klaus Brockhaus, Mar 24 2007
STATUS
approved