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Search: id:A080736
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A080736 Multiplicative function defined by a(1)=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. +0
2
1, 0, 2, 2, 4, 0, 6, 4, 6, 0, 10, 4, 12, 0, 8, 8, 16, 0, 18, 8, 12, 0, 22, 8, 20, 0, 18, 12, 28, 0, 30, 16, 20, 0, 24, 12, 36, 0, 24, 16, 40, 0, 42, 20, 24, 0, 46, 16, 42, 0, 32, 24, 52, 0, 40, 24, 36, 0, 58, 16, 60, 0, 36, 32, 48, 0, 66, 32, 44, 0, 70, 24, 72, 0, 40, 36, 60, 0, 78, 32 (list; graph; listen)
OFFSET

1,3

PROGRAM

(PARI) {for(n=1, 81, f=factor(n); print1(if(n==1, 1, if(f[1, 1]==2&&f[1, 2]==1, 0, prod(j=1, matsize(f)[1], eulerphi(f[j, 1]^f[j, 2])))), ", "))}

CROSSREFS

Cf. A080737.

Sequence in context: A127786 A030207 A061006 this_sequence A144412 A113750 A004565

Adjacent sequences: A080733 A080734 A080735 this_sequence A080737 A080738 A080739

KEYWORD

nonn,easy,mult

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com), Mar 08 2003

EXTENSIONS

More terms and PARI code from Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Mar 10 2003

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Last modified November 30 13:13 EST 2009. Contains 167758 sequences.


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