A050680 - OEIS

%I #21 Sep 04 2021 21:08:05

%S 5,10,12,13,31,38,43,49,51,55,59,60,76,83,85,97,117,118

%N Positions of 3's in A048288.

%H Patrick De Geest, <a href="http://www.worldofnumbers.com/revfact.htm">Reversed Smarandache Concatenated Numbers, Prime factors from n down to 1</a>

%H M. Fleuren, <a href="http://www.gallup.unm.edu/~smarandache/michafleuren.htm">Factors and primes of Smarandache sequences</a>.

%H M. Fleuren, <a href="http://www.gallup.unm.edu/~smarandache/micha.txt">Smarandache Factors and Reverse factors</a>

%H Carlos Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_008.htm">Puzzle 8. Primes by Listing</a>, The Prime Puzzles and Problems Connection.

%Y Cf. A000422, A046462, A048288, A050679, A050681, A050682.

%K nonn,base,hard,less,more

%O 1,1

%A _Patrick De Geest_, Aug 15 1999

%E a(13)-a(16) from _Sean A. Irvine_, Aug 17 2021

%E Offset changed to 1 by and a(17)-a(18) from _Jinyuan Wang_, Sep 04 2021