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%I #7 Oct 12 2014 21:18:06
%S 9,15,27,57,81,177,243,393,579,729,849,1257,2187,4197,4143,5853,6561,
%T 17817,17781,19683,56157,59049,104289,104277,154509
%N Multiples of 3 in A247665 in order of appearance.
%C The initial multiples of 3 occur at positions 6,13,28,57,115,231, ... - conjecturally, for n > 13, A247665(n) is a multiple of 3 iff n = 29*2^k-1, k >= 0.
%e Table showing index where multiples of 3 appear, the multiple of 3, and the number of different prime factors of that term:
%e 6 9 1
%e 13 15 2
%e 28 27 1
%e 57 57 2
%e 115 81 1
%e 231 177 2
%e 463 243 1
%e 927 393 2
%e 1855 579 2
%e 3711 729 1
%e 7423 849 2
%e 14847 1257 2
%e 29695 2187 1
%e 59391 4197 2
%e 118783 4143 2
%e 237567 5853 2
%e 475135 6561 1
%e 950271 17817 2
%e 1900543 17781 2
%e 3801087 19683 1
%e 7602175 56157 2
%e 15204351 59049 1
%e 30408703 104289 2
%e 60817407 104277 2
%e 121634815 154509 2
%Y Cf. A247665, A248379 (multiples of 2).
%K nonn,more
%O 1,1
%A _Russ Cox_ and _N. J. A. Sloane_, Oct 12 2014
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