This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A023516 #22 Sep 08 2022 08:44:47
%S A023516 0,1,2,2,2,2,3,3,2,3,2,3,2,2,3,4,3,3,3,3,2,3,3,3,3,3,3,4,3,2,4,2,3,2,
%T A023516 4,3,3,4,3,4,4,3,3,3,3,3,3,3,3,4,2,3,3,4,4,4,4,4,3,4,2,3,4,2,4,4,3,3,
%U A023516 3,3,3,3,3,4,3,3,4,3,2,4
%N A023516 Number of distinct prime divisors of prime(n)*prime(n-1) - 1.
%C A023516 This is taking prime(0)=1 (see first comment in A023515). - _Vincenzo Librandi_, Apr 27 2019
%H A023516 Vincenzo Librandi, <a href="/A023516/b023516.txt">Table of n, a(n) for n = 1..10000</a>
%F A023516 a(n) = A001221(A023515(n)).
%p A023516 0,seq(nops(numtheory:-factorset(ithprime(n)*ithprime(n-1)-1)),n=2..120); # _Muniru A Asiru_, Apr 29 2019
%t A023516 Prepend[Table[PrimeNu[Prime[n] Prime[n-1] - 1], {n, 2, 80}],0] (* _Vincenzo Librandi_, Apr 27 2019 *)
%o A023516 (Magma) [#PrimeDivisors(NthPrime(n)*(NthPrime(n-1))-1): n in [1..100]]; // _Vincenzo Librandi_, Apr 27 2019
%o A023516 (PARI) a(n) = if (n==1, 0, omega(prime(n)*prime(n-1) - 1)); \\ _Michel Marcus_, Apr 30 2019
%Y A023516 Cf. A023515, A023524, A023568, A023575, A023582, A023589.
%K A023516 nonn
%O A023516 1,3
%A A023516 _Clark Kimberling_