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Search: id:A074313
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| A074313 |
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a(n) = the maximal length of a sequence of primes {s_1 = prime(n), s_2 = f(s1), s_3 = f(s_2), ....} formed by repeated application of f(m) = Floor(m/2) on prime(n). |
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+0
3
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| 1, 1, 2, 2, 3, 1, 1, 1, 4, 1, 1, 1, 1, 1, 5, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 3, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 2, 1, 1, 1, 1
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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The smallest value of n such that a(n) = 6 is n = 417.
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EXAMPLE
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To compute a(9): prime(9) = 23, f(23) = 11, f(11) = 5, f(5) = 2, f(2) = 1, where f(m) = Floor(m/2). Hence the sequence (of length 4) 23, 11, 5, 2 is the sequence of primes of maximal length formed by repeated application of f to prime(9) = 23. Therefore a(9) = 4.
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MATHEMATICA
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f[n_] := Module[{i}, i = 0; m = n; While[PrimeQ[m], m = Floor[m/2]; i++ ]; i]; Table[f[Prime[i]], {i, 1, 100}]
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CROSSREFS
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Sequence in context: A084189 A084352 A106797 this_sequence A066422 A092779 A078827
Adjacent sequences: A074310 A074311 A074312 this_sequence A074314 A074315 A074316
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KEYWORD
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easy,nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Sep 22 2002
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