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 A359069 #20 Jan 31 2023 08:32:34 %S A359069 3,59,47,79,347,6343,56711,4523 %N A359069 Smallest prime p such that p^(2n-1) - 1 is the product of 2n-1 distinct primes. %C A359069 a(9) > 113500. %C A359069 a(9) > 1000000, a(10) > 237000, a(11) > 209021. - _Sean A. Irvine_, Jan 10 2023 %C A359069 a(n)-1 is squarefree for all n. - _Chai Wah Wu_, Jan 30 2023 %e A359069 a(3) = 47 since 47^(2*3-1) - 1 = 229345006 = 2*11*23*31*14621 is the product of 5 distinct primes and 47 is the smallest prime number with this property. %o A359069 (PARI) isok(p, n) = my(f=factor(p^(2*n-1)-1)); issquarefree(f) && (omega(f) == 2*n-1); %o A359069 a(n) = my(p=2); while (!isok(p, n), p=nextprime(p+1)); p; \\ _Michel Marcus_, Dec 15 2022 %Y A359069 Cf. A001597, A005117, A045542, A280005, A359070. %K A359069 nonn,hard,more %O A359069 1,1 %A A359069 _Kevin P. Thompson_, Dec 15 2022