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A195153 Irregular triangle read by rows in which row n lists numbers d-1 that do not divide n, where d divides n.

%I A195153 #24 Apr 02 2017 00:46:50
%S A195153 2,3,4,5,6,3,7,2,8,4,9,10,5,11,12,6,13,2,4,14,3,7,15,16,5,8,17,18,3,9,
%T A195153 19,2,6,20,10,21,22,5,7,11,23,4,24,12,25,2,8,26,3,6,13,27,28,4,9,14,
%U A195153 29,30,3,7,15,31,2,10,32,16,33,4,6,34,5,8,11,17,35
%N A195153 Irregular triangle read by rows in which row n lists numbers d-1 that do not divide n, where d divides n.
%C A195153 It appears that only rows 3, 4, 6, 8, 12, 24 have the property that all their members are primes. See the example. See also the comment at A018253.
%H A195153 T. D. Noe, <a href="/A195153/b195153.txt">Rows n = 3..1000, flattened</a>
%e A195153 Written as an irregular triangle:
%e A195153 2,
%e A195153 3,
%e A195153 4,
%e A195153 5,
%e A195153 6,
%e A195153 3, 7,
%e A195153 2, 8,
%e A195153 4, 9,
%e A195153 10,
%e A195153 5, 11,
%e A195153 12,
%e A195153 6, 13,
%e A195153 2, 4, 14,
%e A195153 3, 7, 15,
%e A195153 16,
%e A195153 5, 8, 17,
%e A195153 18,
%e A195153 3, 9, 19,
%e A195153 2, 6, 20,
%e A195153 10, 21,
%e A195153 22,
%e A195153 5, 7, 11, 23
%t A195153 Flatten[Table[d = Divisors[n]; Select[Rest[d-1], Mod[n, #] > 0 &], {n, 3 , 100}]] (* _T. D. Noe_, Sep 23 2011 *)
%Y A195153 Cf. A018253, A027750, A173540, A195150.
%K A195153 nonn,tabf
%O A195153 3,1
%A A195153 _Omar E. Pol_, Sep 19 2011