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Search: id:A132794
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| A132794 |
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Numbers n such that sigma(phi(n))-phi(n)-1=phi(sigma(n)-n-1). |
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+0
2
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OFFSET
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1,1
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COMMENT
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Used sigma(n)-n-1, namely the sum of proper divisors minus 1.
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MAPLE
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with(numtheory); P:=proc(n) local i, j, k; for i from 1 by 1 to n do j:=sigma(phi(i))-phi(i)-1; k:=phi(sigma(i)-i-1); if j=k then print(i); fi; od; end: P(150000);
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CROSSREFS
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Cf. A000010, A000203, A001229, A018784, A033632, A132793.
Sequence in context: A024623 A027291 A048952 this_sequence A079666 A048230 A073433
Adjacent sequences: A132791 A132792 A132793 this_sequence A132795 A132796 A132797
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KEYWORD
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hard,more,nonn
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AUTHOR
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Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), Aug 31 2007
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