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 A247861 #11 Jun 16 2015 19:18:54 %S A247861 1,80,3988,49,4848,4,86,6,8,7720309,62862,54486,526046,890244,0,20, %T A247861 893,48,540,17,38622,5369,31800,6,54,86,958,56,226,92,0,5,2501,3, %U A247861 43216,548626296,61,8,7,1,40805,9544,492,8,5364864,443,344,495658,88,8,39,254,706,15884607,88712,5,7,41662,40,0,2,7,77,15,14,1704666 %N A247861 Prime sieve of Phi. %H A247861 Manfred Scheucher, <a href="/A247861/b247861.txt">Table of n, a(n) for n = 1..385</a> %H A247861 Manfred Scheucher, <a href="/A247861/a247861.sage.txt">Sage Script</a> %e A247861 Find the first occurrence of prime 2 in the digits of Phi (only 40 digits in this illustration): %e A247861 161803398874989484820458683436563811772..., and replace it with a space: %e A247861 1618033988749894848 0458683436563811772... Repeat the process with 3: %e A247861 16180 3988749894848 0458683436563811772... Then 5: %e A247861 16180 3988749894848 04 8683436563811772... Then 7: %e A247861 16180 3988 49894848 04 8683436563811772... Then 11, 13, 17, etc., until the first occurrence of every prime is eliminated from the digits of Phi. %e A247861 1 80 3988 49 4848 04 86 6 8 772... Then consolidate gaps between the remaining digits into a single comma: %e A247861 1,80,3988,49,4848,4,86,6,8,7720309,... to produce the first terms in the prime sieve of Phi. %Y A247861 Cf. A001622, A247747, A245770. %K A247861 nonn,easy %O A247861 1,2 %A A247861 _Gil Broussard_, Sep 25 2014 %E A247861 Corrected and extended by _Manfred Scheucher_, Jun 05 2015