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 A276962 #32 Oct 02 2017 03:59:38 %S A276962 20,62,84,368,410,614,720,740,762,1230,1280,1988,1998,2064,2100,2268, %T A276962 2312,2468,2678,2940,3002,3324,3392,3462,3768,3848,3968,4178,4244, %U A276962 4680,4968,5022,5024,5198,5304,5382,5624,5822,5850,6048,6248,6338,6354,6398,6428 %N A276962 Numbers n such that n^17 - 1 is semiprime. %C A276962 Least number such that n^17-1 and n^17+1 are both semiprime is 93888. - _Altug Alkan_, Sep 30 2016 %e A276962 a(1) = 20 because 20^17-1 = 13107199999999999999999 = 19*689852631578947368421 is the first occurrence of n^17 - 1 as a product of two distinct primes. %t A276962 Select[Range[3000],PrimeOmega[#^17-1] == 2 &] %o A276962 (PARI) isok(n) = bigomega(n^17-1)==2; \\ _Michel Marcus_, Sep 23 2016 %o A276962 (PARI) lista(nn) = forprime(p=2, nn, if(ispseudoprime(((p+1)^17-1)/p), print1(p+1, ", "))); \\ _Altug Alkan_, Sep 30 2016 %Y A276962 Cf. A001358, A010805, A104494. %K A276962 nonn %O A276962 1,1 %A A276962 _Gary E. Davis_, Sep 22 2016 %E A276962 More terms from _Altug Alkan_, Sep 30 2016