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 A089523 #15 Feb 16 2025 08:32:51 %S A089523 5,13,37,61,73,157,193,277,313,389,397,421,457,461,509,541,569,613, %T A089523 661,673,733,757,769,797,857,877,929,997,1093,1109,1153,1201,1213, %U A089523 1217,1229,1237,1289,1301,1321,1381,1409,1429,1453,1481,1553,1609,1621,1657 %N A089523 Primes p such that mu(p+1) = 1; that is, p+1 is squarefree and has an even number of distinct prime factors, where mu is the Moebius function. %H A089523 Robert Israel, <a href="/A089523/b089523.txt">Table of n, a(n) for n = 1..10000</a> %H A089523 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MoebiusFunction.html">Moebius Function</a> %p A089523 select(n -> isprime(n) and numtheory:-mobius(n+1)=1, [seq(i,i=1..2000,4)]); # _Robert Israel_, Aug 16 2018 %t A089523 Select[Prime[Range[300]], MoebiusMu[ #+1]==1&] %o A089523 (PARI) isok(p) = isprime(p) && (moebius(p+1) == 1); \\ _Michel Marcus_, Aug 16 2018 %o A089523 (Magma) [p: p in PrimesUpTo(2000) | MoebiusMu(p+1) eq 1]; // _Vincenzo Librandi_, Aug 17 2018 %Y A089523 Cf. A089495 (mu(p+1) for prime p), A049098 (primes p with mu(p+1)=0), A078329 (primes p with mu(p+1)=-1). %K A089523 nonn %O A089523 1,1 %A A089523 _T. D. Noe_, Nov 06 2003