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Search: id:A122411
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| A122411 |
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a(n) = sum of primes p's for those k's, 2 <= k <= n, where GCD(k,n) = p^j >1. (a(1) = 0.). |
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+0
2
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| 0, 2, 3, 4, 5, 7, 7, 8, 9, 13, 11, 14, 13, 19, 22, 16, 17, 21, 19, 26, 32, 31, 23, 28, 25, 37, 27, 38, 29, 38, 31, 32, 52, 49, 58, 42, 37, 55, 62, 52, 41, 56, 43, 62, 66, 67, 47, 56, 49, 65, 82, 74, 53, 63, 94, 76, 92, 85, 59, 76, 61, 91, 96, 64, 112, 92, 67, 98, 112, 106, 71
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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The integers k, 2 <= k <= 12, where GCD(k,12) = a power of a prime are 2,3,4,8,9 and 10. GCD(2,12) = 2^1, GCD(3,12) = 3^1, GCD(4,12) = 2^2, GCD(8, 12) = 2^2, GCD(9,12) = 3^1 and GCD(10,12) = 2^1. The sum of the prime bases of the prime-powers is 2+3+2+2+3+2 = 14. So a(12) = 14.
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MATHEMATICA
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f[n_] := Plus @@ First /@ Flatten[Select[FactorInteger[GCD[Range[n], n]], Length[ # ] == 1 &], 1]; Table[f[n], {n, 80}] (*Chandler*)
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CROSSREFS
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Cf. A122410.
Sequence in context: A034152 A114707 A000015 this_sequence A117174 A022473 A082352
Adjacent sequences: A122408 A122409 A122410 this_sequence A122412 A122413 A122414
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Sep 02 2006
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EXTENSIONS
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Corrected and extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Sep 06 2006
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