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Search: id:A079833
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| A079833 |
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Define f(n) = n + tau(n), then a(n) = smallest prime of the type f(f(f...f(n)))). |
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2
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| 2, 7, 5, 7, 7, 71, 71, 71, 71, 71, 13, 71, 19, 71, 19, 71, 19, 71, 71, 71, 71, 71, 71, 71, 71, 71, 31, 71, 31, 71, 37, 71, 37, 71, 43, 59, 43, 71, 43, 811, 43, 71, 59, 71, 59, 71, 811, 811, 811, 71, 59, 811, 59, 811, 59, 71, 61, 811, 61, 163, 73, 811, 73, 71, 73, 811, 73
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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a(6) = 71 as f(6) = 10, f(10) = 14, f(14) = 18, f(18) = 24, f(24) = 32, f(32) = 38, f(38) = 42, f(42) = 50, f(50) = 56, f(56) = 64, f(64) = 64 +7 = 71.
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PROGRAM
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(PARI) { a(n) = local(k, m); k=1; m=n; while(1, m=m+numdiv(m); if(isprime(m), return(m)); k++ ) } (Alekseyev)
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CROSSREFS
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Cf. A079834.
Sequence in context: A119929 A019825 A097157 this_sequence A010593 A117931 A011051
Adjacent sequences: A079830 A079831 A079832 this_sequence A079834 A079835 A079836
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Feb 12 2003
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EXTENSIONS
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More terms from Max Alekseyev (maxal(AT)cs.ucsd.edu), Apr 19 2005
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