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%I A115103 #18 May 08 2022 17:14:11
%S A115103 5,19,29,43,67,89,151,173,197,233,271,283,307,317,349,461,491,569,571,
%T A115103 593,653,701,739,751,787,857,859,907,919,1013,1061,1097,1277,1291,
%U A115103 1303,1483,1667,1747,1831,1867,1889,1913,1973,2003,2083,2131,2311,2357,2393
%N A115103 Primes p such that p-1 and p+1 have the same number of prime factors with multiplicity.
%H A115103 Alois P. Heinz, <a href="/A115103/b115103.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 terms from Vincenzo Librandi)
%e A115103 19-1 = 2*3*3 has 3 factors. 19+1 = 2*2*5 has 3 factors. So 19 is in the table.
%p A115103 isA115103 := proc(n)
%p A115103     if not type(n,prime) then
%p A115103         return false;
%p A115103     end if;
%p A115103     if numtheory[bigomega](n-1) <> numtheory[bigomega](n+1) then
%p A115103         false;
%p A115103     else
%p A115103         true ;
%p A115103     end if ;
%p A115103 end proc:
%p A115103 for n from 2 to 3000 do
%p A115103     if isA115103(n) then
%p A115103         printf("%d,",n) ;
%p A115103     end if;
%p A115103 end do: # _R. J. Mathar_, Feb 13 2019
%p A115103 # second Maple program:
%p A115103 q:= p-> isprime(p) and (f-> f(p+1)=f(p-1))(numtheory[bigomega]):
%p A115103 select(q, [$1..3000])[];  # _Alois P. Heinz_, May 08 2022
%t A115103 Select[Prime[Range[400]],PrimeOmega[#-1]==PrimeOmega[#+1]&] (* _Harvey P. Dale_, Apr 26 2014 *)
%o A115103 (PARI) g(n) = forprime(x=1,n,p1=bigomega(x-1);p2=bigomega(x+1);if(p1==p2,print1(x",")))
%Y A115103 Cf. A067386 (without multiplicity), A323498, A323536, A323537.
%K A115103 easy,nonn
%O A115103 1,1
%A A115103 _Cino Hilliard_, Mar 02 2006

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