OFFSET
1,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
EXAMPLE
a(1) = 112 because (3*37)+1 = (2^4) * 7 = 112.
a(2) = 120 because (7*17)+1 = (2^3) * 3 * 5 = 120.
a(3) = 162 because (7*23)+1 = 2 * (3^4) = 162.
MATHEMATICA
f[n_] := Plus @@ Last /@ FactorInteger[n]; Select[Range[1500], f[ # ] == 5 && f[ # - 1] == 2 &] (* Ray Chandler, Mar 20 2007 *)
PROG
(PARI) v=vector(10000); i=0; for(n=1, 9e99, if(issemi(n)&bigomega(n+1)==5, v[i++]=n+1; if(i==#v, return))); v \\ Charles R Greathouse IV, Feb 14 2011
CROSSREFS
Primes of the form semiprime + 1 are in A005385 (safe primes).
Semiprimes of the form semiprime + 1 are in A109373.
3-almost primes of the form semiprime + 1 are in A109067.
4-almost primes of the form semiprime + 1 are in A109287.
5-almost primes of the form semiprime + 1 are in this sequence.
Least n-almost prime of the form semiprime + 1 are in A128665.
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Aug 25 2005
EXTENSIONS
Extended by Ray Chandler, Mar 20 2007
STATUS
approved