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Composites in base 10 that remain composite in exactly eight bases b, 2 <= b <= 10, expansions interpreted as decimal numbers.
7

%I #15 Apr 10 2024 09:16:11

%S 4,6,12,26,27,35,38,45,46,48,49,50,52,56,57,58,63,64,65,66,68,77,81,

%T 82,84,85,88,95,105,116,117,118,119,121,122,134,136,138,142,153,154,

%U 161,165,166,171,175,176,187,188,190,192,195,207,208,218,219,220,225

%N Composites in base 10 that remain composite in exactly eight bases b, 2 <= b <= 10, expansions interpreted as decimal numbers.

%H Sebastian Petzelberger, <a href="/A256350/b256350.txt">Table of n, a(n) for n = 1..10000</a>

%H Carlos Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_024.htm">PP&P Puzzle 24: Primes in several bases</a>, The Prime Puzzles & Problems Connection.

%Y Cf. A052026, A256350-A256356, A038537, A052027-A052033, A084482, A236356.

%K nonn,base

%O 1,1

%A _Sebastian Petzelberger_, Mar 25 2015