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 A260867 #8 Nov 13 2018 07:47:49 %S A260867 35,161,55,35,115,35,115,35,77,209,473,253,55,77,35,235,247,55,35,35, %T A260867 899,119,1003,415,143,35,335,95,299,497,203,575,35,247,323,95,77,437, %U A260867 901,35,55,473,35,1457,77,55,517,35,235,493,161,535,209,115,95,1067,689,323,35,1199,1313,355,77,815,635,869,235,119,551,55,115 %N A260867 Least k > 1 that divides A260868(n) + 2^k - 2. %C A260867 For all numbers N not listed in A260868, the least k > 1 that divides N + 2^k - 2 is equal to the least prime factor of N. %C A260867 It appears that the range of this sequence is A267999. For example, 155 occurs first somewhat late for N = 2729. - Corrected by _Thomas Ordowski_, Oct 27 2018 %o A260867 (PARI) my(aa(n)=for(k=2,9e9,Mod(2,k)^k+n-2||return(k)));for(n=2,1e5,aa(n)==factor(n)[1,1]||print1(aa(n)",")) %K A260867 nonn %O A260867 1,1 %A A260867 _M. F. Hasler_, Aug 11 2015