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Search: id:A105998
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| A105998 |
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Semiprime function n -> A0013458(n) applied four times to n. |
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+0
6
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| 77, 119, 219, 235, 377, 381, 566, 634, 721, 779, 998, 1006, 1126, 1282, 1294, 1563, 1642, 1745, 1853, 1959, 1961, 2209, 2402, 2483, 2554, 2785, 3005, 3149, 3173, 3242, 3481, 3574, 3587, 3622, 4101, 4282, 4471, 4681, 4714, 4798, 4859, 4882, 5095, 5201
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a(n) = A001358(A001358(A001358(A001358(n)))).
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EXAMPLE
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a(1) = semiprime(semiprime(semiprime(semiprime(1)))) = semiprime(semiprime(semiprime(4))) = semiprime(semiprime(10)) = semiprime(26) = 77.
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MATHEMATICA
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f[n_] := Plus @@ Flatten[ Table[ # [[2]], {1}] & /@ FactorInteger[ n]]; t = Select[ Range[ 5210], f[ # ] == 2 &]; Table[ Nest[ t[[ # ]] &, n, 4], {n, 45}] (from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 30 2005)
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CROSSREFS
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Cf. A001358, A007097, A091022, A105997, A105999.
Sequence in context: A061671 A064902 A127335 this_sequence A039444 A118611 A072431
Adjacent sequences: A105995 A105996 A105997 this_sequence A105999 A106000 A106001
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Apr 29 2005
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 30 2005
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