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 A023504 #20 Sep 08 2024 22:33:19
%S A023504 0,1,2,1,1,2,4,2,1,2,1,2,3,1,1,2,1,2,1,1,3,1,1,3,5,2,1,1,3,4,2,1,3,1,
%T A023504 2,2,2,4,1,2,1,2,1,6,2,2,1,1,1,2,3,1,4,3,8,1,2,3,2,3,1,2,2,1,3,2,1,4,
%U A023504 1,2,5,1,1,2,3,1,2,2,4,3,1,2,1,4,1,1,6,3,2,1,1,1,5,2,1,1,2,3,2
%N A023504 Maximum exponent in the prime factorization of prime(n) - 1.
%H A023504 Harvey P. Dale, <a href="/A023504/b023504.txt">Table of n, a(n) for n = 1..1000</a>
%F A023504 a(n) = A051903(A006093(n)) . - _R. J. Mathar_, Feb 06 2019
%e A023504 The seventh prime is 17, and 16 = 2^4, so a(7) = 4.
%e A023504 The eighth prime is 19, and 18 = 2^1 * 3^2, and since 2 is the greater exponent, a(8) = 2.
%t A023504 Join[{0}, Max[FactorInteger[#][[All, 2]]]&/@(Prime[Range[2, 120]] - 1)] (* _Harvey P. Dale_, Aug 29 2017 *)
%o A023504 (PARI) a(n) = if(n == 1, 0, vecmax(factor(prime(n) - 1)[, 2])); \\ _Amiram Eldar_, Sep 08 2024
%Y A023504 Cf. A006093, A023510, A051903.
%K A023504 nonn,easy
%O A023504 1,3
%A A023504 _Clark Kimberling_