A342258 - OEIS

%I #15 Sep 19 2024 04:19:00

%S 62,74,188,194,195,275,278,363,398,422,423,483,494,495,614,662,663,

%T 747,758,764,782,867,1028,1071,1094,1095,1235,1238,1268,1394,1419,

%U 1454,1658,1659,1682,1844,1910,1916,1955,1970,2043,2067,2138,2139,2223,2235,2247,2259

%N Numbers k such that Omega(k-1) = Omega(k)-1 and Omega(k+1) = Omega(k)+1, where Omega is the number of prime divisors counted with multiplicity, A001222.

%H Hugo Pfoertner, <a href="/A342258/b342258.txt">Table of n, a(n) for n = 1..10001</a>

%t seq[nmax_] := Module[{om}, om[n_] := om[n] = PrimeOmega[n]; Select[Range[2, nmax], om[# - 1] == om[#] - 1 && om[# + 1] == om[#] + 1 &]]; seq[2500] (* _Amiram Eldar_, Sep 19 2024 *)

%o (PARI) for(n=3,2300,my(bO=bigomega(n));if(bigomega(n-1)==bO-1&&bigomega(n+1)==bO+1,print1(n,", ")))

%Y Cf. A001222, A342259.

%K nonn

%O 1,1

%A _Hugo Pfoertner_, Mar 07 2021