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 A173951 #8 Mar 19 2013 00:53:21
%S A173951 32,104,320,968,2624,2912,7808,8744,23360,25376,26240,70016,75920,
%T A173951 78728,209984,212576,227552,233600,236192,629888,638312,682448,700160,
%U A173951 708584,1889600,1897376,1915520,2047136,2054912,2099840,2117984,2125760
%N A173951 Positive integers with the property that if the base-3 representation is reversed the result is twice the original number.
%C A173951 The number of terms of this sequence containing n ternary digits is given by {d(n)}={0,0,0,1,1,1,1,2,2,3,3,5,5,8,8,13,13,21,...} for n=1,2,3,... and thus appears to be essentially the doubling-up of the Fibonacci numbers A103609. For example, 2624 = 10121012(base-3) and 2912 = 10222212(base-3) are the only two terms that have 8 digits when written in base 3, so d(8)=2.
%C A173951 (This conjecture is correct - see A223077. - _N. J. A. Sloane_, Mar 19 2013)
%C A173951 All terms of sequence A173952, defined by b(1)=32 and, for n>1, b(n)=9*b(n-1)+32, appear to be terms of the above sequence {a(n)}; in fact each term b(n) appears to be the largest term of {a(k)} that has 2n+2 digits when written in base 3.
%Y A173951 Cf. A103609, A173952, A223077, A214927.
%K A173951 nonn,base
%O A173951 1,1
%A A173951 _John W. Layman_, Mar 03 2010