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 A277875 #7 Nov 04 2016 04:54:49
%S A277875 1,7,1,1,1,19,13,1,1,1,1,7,5,11,1,1,1,7,11,1,1,1,1,1,1,7,5,1,1,7,1,1,
%T A277875 1,1,1,11,5,1,1,1,1,1,1,1,1,7,5,1,1,7,1,1,1,7,1,1,1,7,5,11,1,7,5,1,1,
%U A277875 7,1,1,1,11,1,1,1,1,1,11,1,7,1,1,1,1,1,11,1,1,1,1,1,1,1,1,1,7,1,1,1,1,1,1
%N A277875 a(n) is the odd multiplier q in the expressions 2*(q*2^n - 1) and 2*(q*3^n - 1) of numbers A277215(n) and A277874(n), respectively.
%C A277875 The position numbers for odd numbers 5, 7, 11, 13 and 19 for the first 200 numbers in the sequence are listed in the Comments section of A277215.
%e A277875 a(0) = 1 since 0 = 2*(1*2^0 - 1) is the start and end of the first alternating sequence of 1 element and the maximum of its trajectory.
%e A277875 a(5) = 19 since 9232 = 2*(19*3^5 - 1) is the last element in the first alternating sequence of 11 elements - 1214, 607, 1822, 911, 2734, 1367, 4102, 2051, 6154, 3077, 9232 - that ends in the trajectory maximum.
%t A277875 (* we use function altdata[] from A277215 *)
%t A277875 a277875[n_]:=Map[#[[2]]&, altdata[2,n]]
%t A277875 Join[{1,7}, a277875[99]] (* sequence data *)
%Y A277875 Cf. A277215, A277874.
%K A277875 nonn
%O A277875 0,2
%A A277875 _Hartmut F. W. Hoft_, Nov 03 2016