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 A151794 #10 Jun 13 2015 00:52:44
%S A151794 2,4,6,14,26,54,106,214,426,854,1706,3414,6826,13654,27306,54614,
%T A151794 109226,218454,436906,873814,1747626,3495254,6990506,13981014,
%U A151794 27962026,55924054,111848106,223696214,447392426,894784854,1789569706,3579139414,7158278826,14316557654
%N A151794 a(1)=2, a(2)=4, a(3)=6; a(n+3) = a(n+2)+ 2*a(n), n>=1.
%C A151794 Consider the following coin tossing experiment. Let n >= 1 be a predetermined integer. We toss an unbiased coin sequentially. For each outcome, we score two points for a head (H) and one point for a tail (T). The coin is tossed until the total score reaches n or jumps from n-1 to n+1. The results of the tosses are written in a linear array. Then the probability of non-occurrence of double heads (HH) is given by p(n) = a(n) / 2^n, n>=1.
%D A151794 Bhanu K. S, Deshpande M. N. & Cholkar C. P. (2006): Coin tossing -Some Surprising Results, International Journal of Mathematical Education In Science and Technology, Vol.37, No.1, pp.115-119.
%H A151794 Colin Barker, <a href="/A151794/b151794.txt">Table of n, a(n) for n = 1..1000</a>
%H A151794 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (1,2).
%F A151794 G.f.: 2*x*(-x+x^2-1)/((1+x)*(2*x-1)).
%F A151794 a(n) = A084214(n), n>1.
%F A151794 a(n) = A168648(n-2), n>2.
%F A151794 a(n) = 2*A048573(n-2), n>1.
%F A151794 a(n) = (4*(-1)^n+5*2^n)/6 for n>1. - _Colin Barker_, Jun 12 2015
%t A151794 Join[{2},LinearRecurrence[{1,2},{4,6},40]] (* _Harvey P. Dale_, Oct 19 2012 *)
%o A151794 (PARI) Vec(2*x*(-x+x^2-1)/((1+x)*(2*x-1)) + O(x^100)) \\ _Colin Barker_, Jun 12 2015
%K A151794 nonn,easy
%O A151794 1,1
%A A151794 K. S. Bhanu (bhanu_105(AT)yahoo.com), Jun 21 2009