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 A238984 a(n+1) is the product of the last three digits of the sequence up to a(n), start with a(0)=2. 6
 2, 8, 32, 48, 64, 192, 18, 16, 48, 192, 18, 16, 48, 192, 18, 16, 48, 192, 18, 16, 48, 192, 18, 16, 48, 192, 18, 16, 48, 192, 18, 16, 48, 192, 18, 16, 48, 192, 18, 16, 48, 192, 18, 16, 48, 192, 18, 16, 48, 192, 18, 16, 48, 192, 18, 16, 48, 192, 18, 16, 48 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Additional rule: if there are fewer than k=3 digits in the sequence so far, then it is "extended to the left" with the first digit (i.e., that digit is repeated as often as necessary). For any starting value, the sequence obtained through these rules ends either in repeating 0's, or in repeating 1's, or in the cycle (16,48,192,18). So 2 is the least starting value for which this nontrivial cycle is entered, after 5 iterations, at a(5)=192. LINKS E. Angelini, Multiplication by themselves of the last k digits. FORMULA a(n+4)=a(n) for n > 4. EXAMPLE a(1) = 2*2*2 = 8 (here the initial digit is used 3 times), a(2) = 2*2*8 = 32 (here the initial digit is used twice to get k=3 factors), a(3) = 8*3*2 = 48, ... PROG (PARI) A238984(n, a=2, k=3, print_all=0)={my(L=if(a, digits(a), [0]), S=Str(-k"..")); while(#L

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Last modified March 20 21:49 EDT 2019. Contains 321352 sequences. (Running on oeis4.)