OFFSET
1,2
COMMENTS
Semiprime(n)/2 and semiprime(n+1)/2 are consecutive primes.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..2000
EXAMPLE
a(1)=1 because both semiprime(1)=4 and semiprime(2)=6 are even
a(2)=4 because both semiprime(4)=10 and semiprime(5)=14 are even.
MATHEMATICA
Flatten[Position[Partition[Select[Range[10000], PrimeOmega[#]==2&], 2, 1], _?(EvenQ[First[#]]&&EvenQ[Last[#]]&), {1}, Heads->False]] (* Harvey P. Dale, Apr 19 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Mar 29 2010
EXTENSIONS
Edited and corrected by Ray Chandler, Apr 07 2010
STATUS
approved