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Search: id:A080737
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| A080737 |
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a(1)=a(2)=0, a(2^r) = phi(2^r) (r>1), a(p^r) = phi(p^r) (p odd prime, r>=1), where phi is Euler's function A000010 and in general if n = Product p_i^e_i, a(n) = Sum a(p_i^e_i). |
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+0
8
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| 0, 0, 2, 2, 4, 2, 6, 4, 6, 4, 10, 4, 12, 6, 6, 8, 16, 6, 18, 6, 8, 10, 22, 6, 20, 12, 18, 8, 28, 6, 30, 16, 12, 16, 10, 8, 36, 18, 14, 8, 40, 8, 42, 12, 10, 22, 46, 10, 42, 20, 18, 14, 52, 18, 14, 10, 20, 28, 58, 8, 60, 30, 12, 32, 16, 12, 66, 18, 24, 10, 70, 10, 72, 36, 22, 20, 16, 14
(list; graph; listen)
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OFFSET
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1,3
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REFERENCES
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J. Bamberg, G. Cairns and D. Kilminster, The crystallographic restriction, permutations and Goldbach's conjecture, Amer. Math. Monthly, 110 (March 2003), 202-209.
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PROGRAM
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(PARI) {for(n=1, 78, k=0; if(n>1, f=factor(n); k=sum(j=1, matsize(f)[1], eulerphi(f[j, 1]^f[j, 2])); if(f[1, 1]==2&&f[1, 2]==1, k--)); print1(k, ", "))}
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CROSSREFS
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Cf. A080736, A080738, A080739, A080740, A067240.
See A152455 for another version.
Adjacent sequences: A080734 A080735 A080736 this_sequence A080738 A080739 A080740
Sequence in context: A086296 A096504 A011773 this_sequence A152455 A000010 A003978
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Mar 08 2003
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EXTENSIONS
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More terms and PARI code from Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Mar 10 2003
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