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 A072134 #10 Sep 09 2017 10:38:47
%S A072134 3,5,6,7,17,19,53,55,161,163,485,487,1457,1459,4373,4375,13121,13123,
%T A072134 39365,39367,118097,118099,354293,354295,1062881,1062883,3188645,
%U A072134 3188647,9565937,9565939,28697813,28697815,86093441,86093443,258280325
%N A072134 Second generation sequence in which each number is skipped that can be written as sum of distinct previous entries. To make the first generation we start with all natural numbers: this gives the powers of 2 (A000079). For the second generation we start with the natural numbers from which are removed the numbers of the first generation.
%F A072134 a_n is the union of {3, 6}; the numbers {v_n} where v_0 = 5, v_n=3*v_{n-1}+2; and the numbers u_n = 2 + v_n.
%F A072134 Conjectures from _Colin Barker_, Sep 09 2017: (Start)
%F A072134 G.f.: (3 + 8*x + 2*x^2 - 11*x^3 - 9*x^4 - 3*x^5) / ((1 + x)*(1 - 3*x^2)).
%F A072134 a(n) = -(-1)^n + 3^((n-1)/2)*(1-(-1)^n + sqrt(3) + (-1)^n*sqrt(3)) for n>2.
%F A072134 a(n) = -a(n-1) + 3*a(n-2) + 3*a(n-3) for n>5.
%F A072134 (End)
%e A072134 4 is not in the sequence because it is in A000079.
%e A072134 14 is not in the sequence because 14 = 3+5+6.
%K A072134 nonn
%O A072134 0,1
%A A072134 _Floor van Lamoen_, Jun 26 2002