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 A339699 #19 Dec 25 2020 11:10:15
%S A339699 5,23,25,31,41,43,47,53,67,101,109,113,127,137,141,149,155,187,191,
%T A339699 195,203,209,253,275,317,322,329,367,389,409,415,503,537,565,613,623,
%U A339699 637,643
%N A339699 Numbers m such that 3^m-1 and 3^m+1 have the same number k of prime factors counted with multiplicity.
%C A339699 Corresponding values of k: {3, 3, 5, 4, 4, 3, 4, 4, 4, 6, 9}.
%e A339699 3^5 - 1 = 242 = 2*11*11, 3^5 + 1 = 244 = 2*2*61 (both are 3-almost primes (A110187)).
%o A339699 (PARI) isok(m) = bigomega(3^m-1) == bigomega(3^m+1); \\ _Michel Marcus_, Dec 14 2020
%Y A339699 Cf. A001222, A057941, A057958.
%K A339699 nonn,more
%O A339699 1,1
%A A339699 _Zak Seidov_, Dec 14 2020