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 A374823 #13 Dec 12 2024 22:55:59 %S A374823 2,3,13,19,37,41,61,73,89,97,109,137,157,181,229,233,241,277,349,373, %T A374823 397,449,569,601,613,641,673,709,733,809,829,853,857,877,881,883,937, %U A374823 997,1049,1069,1097,1117,1153,1193,1201,1213,1237,1249,1361,1409,1433,1549,1621,1657,1669,1693,1789,1801 %N A374823 Primes p such that p-1 is refactorable. %C A374823 Primes p such that p - 1 is divisible by A000005(p-1), the number of divisors of p - 1. %H A374823 Robert Israel, <a href="/A374823/b374823.txt">Table of n, a(n) for n = 1..10000</a> %e A374823 a(4) = 19 is a term because 19 is prime and 18 is divisible by A000005(18) = 6. %p A374823 filter:= p -> isprime(p) and (p-1) mod numtheory:-tau(p-1) = 0: %p A374823 select(filter, [2, seq(i,i=3..10000,2)]); %Y A374823 Intersection of A000040 and A377121. %Y A374823 Includes A158018 and A158014 (except 17). %Y A374823 Cf. A000005, A033950. %K A374823 nonn %O A374823 1,1 %A A374823 _Robert Israel_, Dec 12 2024