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 A217068 #16 Oct 16 2012 17:31:19 %S A217068 7991,4096740829,651,25056,23973,41526,1302,5005333,8175,504,1953, %T A217068 2919396,13737,1054,2257,1708,11521,22313,16350,123098,1008,1584,3906, %U A217068 1887,89027,5335754,27474,59550082,2108,1344,4514,1512,3416,2925,5859,494379,44626,1586993,8557 %N A217068 Least number m such that phi(m-6n) = phi(m) = phi(m+6n) and m is not divisible by n. %C A217068 a(n) has been computed by _Donovan Johnson_ up to 200, but no values were found below 2*10^11 for n=41, 67, 113, 149, 157, 181. %H A217068 F. Firoozbakht, <a href="http://www.primepuzzles.net/puzzles/puzz_466.htm">Puzzle 466. phi(n-1)=phi(n)=phi(n+1)</a>, in C. Rivera's Primepuzzles. %H A217068 S. W. Graham, J. J. Holt and C. Pomerance, <a href="http://www.math.dartmouth.edu/~carlp/phi.pdf">On the solutions to phi(n) = phi(n+k)</a> Number Theory in Progress, K. Gyory, H. Iwaniec, and J. Urbanowicz, eds., vol. 2, de Gruyter, Berlin and New York, 1999, pp. 867-882. %H A217068 Donovan Johnson and Michel Marcus, <a href="/A217068/a217068.txt">a(n) for n=2 to 200, with missing terms shown as 0.</a> %Y A217068 Cf. A000010, A217006. %K A217068 nonn %O A217068 2,1 %A A217068 _Michel Marcus_, Sep 26 2012