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 A269961 #20 Apr 05 2016 09:15:45 %S A269961 3,9,63,129,903,2193,15351,32769,229383,5577073,3899511,8421633, %T A269961 58951431,143167761,1002174327,2147483649,15032385543,36507222033, %U A269961 25550554231,551903297793,3863323084551,9382356062481,65676492437367,140739635904513,985177451331591,2392573810376721,16748016672637047,36170086427459841,25319060499221887,614891469266817297,4304240284867721079,9223372036854775809 %N A269961 Decimal representation of the n-th iteration of Conway’s Game of Life starting with two adjacent two-way infinite rows of ON cells. %C A269961 Empirical observations: %C A269961 The sequence starting with a single row of ON cells is A266382. %C A269961 Every 2^n-1 step of iteration generates the biggest gap (g) between two rows. %C A269961 The prime factors for numbers in this sequence up to the 31st term are: 3,7,11,17,19,31,43,257,331,5419,65537,715827883,77158673929. %e A269961 0th iteration = 11 = 3, 1st iteration = 1001 = 9, 2nd iteration = 111111 = 63, 3rd iteration = 10000001 = 129, 4th iteration = 1110000111 = 903, 5th iteration = 100010010001, 6th iteration = 11101111110111...... %Y A269961 Cf. A266382. %K A269961 nonn %O A269961 0,1 %A A269961 _Brook Estifanos_, Mar 08 2016