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 A268692 #19 Mar 29 2024 19:03:59 %S A268692 1,2,3,6,9,10,13,19,45,46,58,141,271,336,562,601,1128,1635,2718,2920, %T A268692 3933,4351,4729,6556,8349,10851,32641,34039,41050,63732,64738,68173, %U A268692 88690 %N A268692 Numbers k such that 2^(k-1)*(2^k - 1) + 1 is prime (see A134169). %C A268692 The intersection of this sequence with A000043 gives 2, 3, 13, 19, ... which are the indices corresponding to primes just next to perfect numbers (A000396), see A061644. %C A268692 There are prime members of this sequence (271, 601, 4729, ...) which are not in A000043. %C A268692 a(30) > 50000. All the primes corresponding to terms up to a(29) have been certified by the PFGW software performing the Brillhart-Lehmer-Selfridge N-1 test. - _Giovanni Resta_, Apr 11 2016 %C A268692 a(30)-a(32) terms have been certified by the PFGW software performing the Brillhart-Lehmer-Selfridge N-1 test. - _Jorge Coveiro_, Oct 29 2023 %C A268692 a(33) term has been certified by the PFGW software performing the Brillhart-Lehmer-Selfridge N-1 test. - _Jorge Coveiro_, Mar 08 2024 %o A268692 (PARI) for(n=0,10^5,ispseudoprime(2^(n-1)*(2^n-1)+1) && print1(n,", ")) %Y A268692 Cf. A134169, A061644, A000043, A000396, A006516. %K A268692 nonn,more %O A268692 1,2 %A A268692 _Jeppe Stig Nielsen_, Feb 11 2016 %E A268692 a(27)-a(29) from _Giovanni Resta_, Apr 11 2016 %E A268692 a(30)-a(32) from _Jorge Coveiro_, Oct 29 2023 %E A268692 a(33) from _Jorge Coveiro_, Mar 08 2024