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%I #9 Sep 23 2014 09:14:49
%S 4,6,8,20,21,24,40,41,44,46,48,52,60,70,80,81,84,86,88,90,102,204,305,
%T 476,485,600,649,650,660,664,667,669,686,698,720,934,2030,2040,4100,
%U 4680,5000,6010,6011,6014,6016,6018,6040,6044,6046,6048,6060
%N Self-describing sequence. See the sequence as a succession of digits: then a(n) is the position of a prime digit in the sequence.
%C "Prime" digits are 2, 3, 5 and 7.
%e Prime digits are between brackets:
%e Sequence: 4,6,8,(2)0,(2)1,(2)4,40,41,44,46,48,(5)(2),60,(7)0...
%e Digit pos: 4th 6th 8th 20 21st 24th ... = the sequence itself.
%K base,easy,nonn
%O 1,1
%A _Eric Angelini_, Feb 05 2006
%E More terms from _Ray G. Opao_, Sep 23 2014