OFFSET
1,1
COMMENTS
The sequence shows similarity with the Rassias Conjecture ("for any prime p there are two primes p1 and p2 such that p*p1=p1+p2+1, p>2, p2>p1") with p1=p we have p*p=p+p2-1 (see A190272). Generalization can be achieved by removing semiprimarity condition and accepting p^e, e>=2.
LINKS
European Mathematical Society, Newsletter (see book reviews), March 2011, page 46.
EXAMPLE
n=15, 15'=8, a=8+1=9=3^2 -> a(1)=15
MAPLE
seq(`if`(isprime((ithprime(i)^2-ithprime(i)-1))=true, (ithprime(i)^2-ithprime(i)-1)*ithprime(i), NULL), i=1..300);
CROSSREFS
KEYWORD
nonn
AUTHOR
Giorgio Balzarotti, May 07 2011
STATUS
approved