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A248381
Multiples of 3 in A247665 in order of appearance.
2
9, 15, 27, 57, 81, 177, 243, 393, 579, 729, 849, 1257, 2187, 4197, 4143, 5853, 6561, 17817, 17781, 19683, 56157, 59049, 104289, 104277, 154509
OFFSET
1,1
COMMENTS
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.
EXAMPLE
Table showing index where multiples of 3 appear, the multiple of 3, and the number of different prime factors of that term:
6 9 1
13 15 2
28 27 1
57 57 2
115 81 1
231 177 2
463 243 1
927 393 2
1855 579 2
3711 729 1
7423 849 2
14847 1257 2
29695 2187 1
59391 4197 2
118783 4143 2
237567 5853 2
475135 6561 1
950271 17817 2
1900543 17781 2
3801087 19683 1
7602175 56157 2
15204351 59049 1
30408703 104289 2
60817407 104277 2
121634815 154509 2
CROSSREFS
Cf. A247665, A248379 (multiples of 2).
Sequence in context: A046353 A340095 A046356 * A060874 A147511 A124580
KEYWORD
nonn,more
AUTHOR
Russ Cox and N. J. A. Sloane, Oct 12 2014
STATUS
approved