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%I #30 Jun 20 2021 17:15:42
%S 1999,9199,338383,383833,1181881,1881181,1881811,2222929,2922229,
%T 8118181,8188111,8881111,9222229,15551551,15555151,15555511,16166611,
%U 16616161,33333373,33733333,34434343,44334343,44343433,51155551,51515551,55155151,55155511,55515151
%N Primes containing only two distinct digits whose sum of digits is 28, the second perfect number.
%C Calculated by Robert T. McQuaid (robert.mcquaid(AT)headwaters.com).
%H Alois P. Heinz, <a href="/A048518/b048518.txt">Table of n, a(n) for n = 1..21755</a> (first 200 terms from Sean A. Irvine)
%H C. Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_035.htm">Source</a> from Carlos Rivera's Puzzle Site.
%t Select[Prime[Range[3100000]],Count[DigitCount[#],0]==8&&Total[ IntegerDigits[ #]]==28&] (* _Harvey P. Dale_, Jun 11 2016 *)
%Y Cf. A000396, A030291, A048517.
%K nonn,base
%O 1,1
%A _Patrick De Geest_, May 15 1999
%E More terms from _Naohiro Nomoto_, Jul 28 2001
%E Offset corrected by _Sean A. Irvine_, Jun 20 2021
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