A069346 - OEIS

%I #8 Dec 10 2013 20:31:22

%S 2,5,7,13,17,19,23,31,37,41,43,47,53,67,73,83,89,103,107,109,113,127,

%T 131,139,151,157,163,167,179,181,199,211,227,233,239,241,251,257,263,

%U 281,283,293,307,311,313,317,337,347,353,359

%N Primes of the form n - Omega(n), where Omega(n) is the number of prime factors of n, A001222(n).

%C The representation is ambiguous, see A069347.

%H Charles R Greathouse IV, <a href="/A069346/b069346.txt">Table of n, a(n) for n = 1..10000</a>

%e a(10) = 41 = A069345(44) = 44-3 (as 44 = 2*2*11).

%t Select[Table[n - PrimeOmega[n], {n, 1, 400}], PrimeQ] // Union (* _Jean-François Alcover_, Jun 08 2013 *)

%o (PARI) is(n)=for(k=1, log(n)\log(2)+1, if(bigomega(n+k)==k, return(isprime(n)))); 0 \\ _Charles R Greathouse IV_, Dec 10 2013

%Y Cf. A069348, A069356.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Mar 18 2002