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A057522
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a(n+1) = a(n)/2 if 2|a(n), a(n)/3 if 3|a(n), a(n)/5 if 5|a(n), a(n)/7 if 7|a(n), a(n)/11 if 11|a(n), else 13*a(n)+1.
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12
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73, 950, 475, 95, 19, 248, 124, 62, 31, 404, 202, 101, 1314, 657, 219, 73, 950, 475, 95, 19, 248, 124, 62, 31, 404, 202, 101, 1314, 657, 219, 73, 950, 475, 95, 19, 248, 124, 62, 31, 404, 202, 101, 1314, 657, 219, 73, 950, 475, 95, 19, 248, 124, 62, 31, 404, 202
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| This is the `13x+1' map. The `Px+1 map': if x is divisible by any prime < P then divide out these primes one at a time starting with the smallest; otherwise multiply x by P and add 1.
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REFERENCES
| Murad A. AlDamen, Smarandache Notion Journal, "Murad iterating function" [details?].
Murad A. AlDamen, Murad iterating function, Journal of University of Jerash, 2001, to appear.
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LINKS
| Eric Weisstein's World of Mathematics, Collatz problem
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FORMULA
| For n>15, a(n)=a(n-15) [From Harvey P. Dale, May 02 2011]
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EXAMPLE
| 73 -> 19*73+1 = 950, 950 = 2*5^2*19 -> 950/2 = 475, etc.
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MATHEMATICA
| nxt[n_]:=Which[Divisible[n, 2], n/2, Divisible[n, 3], n/3, Divisible[n, 5], n/5, Divisible[n, 7], n/7, Divisible[n, 11], n/11, True, 13n+1]; NestList[nxt, 73, 60] (* From Harvey P. Dale, May 02 2011 *)
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CROSSREFS
| Cf. A057446 (short version), A057216, A057534, A057614.
Sequence in context: A197341 A104907 A123811 * A008400 A090685 A008392
Adjacent sequences: A057519 A057520 A057521 * A057523 A057524 A057525
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KEYWORD
| nonn
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AUTHOR
| Murad A. AlDamen (Divisibility(AT)yahoo.com), Oct 17 2000
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