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 A089188 #14 Jun 29 2024 07:17:21
%S A089188 3,11,59,71,107,179,191,227,239,311,347,419,431,599,659,827,1019,1031,
%T A089188 1091,1319,1427,1487,1607,1619,1787,1871,1931,2027,2087,2111,2267,
%U A089188 2339,2591,2687,2711,2999,3119,3167,3299,3359,3371,3467,3527,3539,3671,3767
%N A089188 Lesser member p of a pair of twin primes such that p-1 is squarefree.
%H A089188 Amiram Eldar, <a href="/A089188/b089188.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1001 from Harvey P. Dale)
%e A089188 71 is a term because it is a prime, 71 + 2 = 73 is a prime, and 71 - 1 = 70 = 2 * 5 * 7 is squarefree.
%e A089188 17 is not a term because 17 - 1 = 2^4.
%t A089188 Select[Transpose[Select[Partition[Prime[Range[600]],2,1],#[[2]]-#[[1]]==2&]][[1]],SquareFreeQ[#-1]&] (* _Harvey P. Dale_, Aug 10 2013 *)
%o A089188 (PARI) pm1th(n) = { c=0; pc=0; forprime(x=2,n, pc++; y=x-1; if(isprime(x+2), if(issquarefree(y), c++; print1(x","); ) ) ); print(); print(c","pc","c/pc+.0) }
%Y A089188 Intersection of A001359 and A039787.
%Y A089188 Cf. A005117.
%K A089188 easy,nonn
%O A089188 1,1
%A A089188 _Cino Hilliard_, Dec 07 2003
%E A089188 Offset corrected by _Amiram Eldar_, Jun 29 2024