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 A308709 Start with 3, divide by 3, multiply by 2, multiply by 3, multiply by 2, repeat. 1
 3, 1, 2, 6, 12, 4, 8, 24, 48, 16, 32, 96, 192, 64, 128, 384, 768, 256, 512, 1536, 3072, 1024, 2048, 6144, 12288, 4096, 8192, 24576, 49152, 16384, 32768, 98304, 196608, 65536, 131072, 393216, 786432, 262144, 524288, 1572864, 3145728, 1048576 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The division by 3 is always possible since it is always preceeded by a multiplication by 3. This sequence arises in the "3x+1" (Collatz) problem. In the rows of A322469, the terms of this sequence appear at the end of any first row which is longer than all previous rows. LINKS Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 4). FORMULA G.f.: x*(3+x+2*x^2+6*x^3)/(1-4*x^4). EXAMPLE 3; /3 => 1; *2 => 2; *3 => 6;  *2 => 12;    /3 => 4; *2 => 8; *3 => 24; *2 => 48 ... MATHEMATICA LinearRecurrence[{0, 0, 0, 4}, {3, 1, 2, 6}, 50] PROG (Python 3) def A308709List(init):     a = init     while True:         yield a         a //= 3         yield a         a <<= 1         yield a         a *= 3         yield a         a <<= 1 a = A308709List(3) print([next(a) for _ in range(42)]) # Peter Luschny, Aug 05 2019 CROSSREFS Cf. A307407, A322469. Sequence in context: A279859 A201655 A049917 * A166197 A010279 A024743 Adjacent sequences:  A308706 A308707 A308708 * A308710 A308711 A308712 KEYWORD nonn,easy AUTHOR Georg Fischer, Aug 05 2019 STATUS approved

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Last modified September 21 08:38 EDT 2020. Contains 337268 sequences. (Running on oeis4.)