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A132741
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Largest divisor of n having the form 2^i*5^j.
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5
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1, 2, 1, 4, 5, 2, 1, 8, 1, 10, 1, 4, 1, 2, 5, 16, 1, 2, 1, 20, 1, 2, 1, 8, 25, 2, 1, 4, 1, 10, 1, 32, 1, 2, 5, 4, 1, 2, 1, 40, 1, 2, 1, 4, 5, 2, 1, 16, 1, 50, 1, 4, 1, 2, 5, 8, 1, 2, 1, 20, 1, 2, 1, 64, 5, 2, 1, 4, 1, 10, 1, 8, 1, 2, 25, 4, 1, 2, 1, 80, 1, 2, 1, 4, 5, 2, 1, 8, 1, 10, 1, 4, 1, 2, 5, 32, 1, 2
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| a(n) = n / A132740(n); a(A003592(n)) = A003592(n);
A051626(a(n)) = 0; A007732(a(n)) = 1.
Multiplicative with a(2^e)=2^e, a(5^e)=5^e and a(p^e)=1 for p=3 or p>=7. - R. J. Mathar, Sep 06 2011
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LINKS
| R. Zumkeller, Table of n, a(n) for n = 1..10000
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FORMULA
| Dirichlet g.f. zeta(s)*(2^s-1)*(5^s-1)/((2^s-2)*(5^s-5)). - R. J. Mathar, Sep 06 2011
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MAPLE
| A132741 := proc(n) local f, a; f := ifactors(n)[2] ; a := 1; for f in ifactors(n)[2] do if op(1, f) =2 then a := a*2^op(2, f) ; elif op(1, f) =5 then a := a*5^op(2, f) ; end if; end do; a; end proc: # R. J. Mathar, Sep 06 2011
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CROSSREFS
| Sequence in context: A159971 A114158 A162407 * A072436 A090077 A163509
Adjacent sequences: A132738 A132739 A132740 * A132742 A132743 A132744
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KEYWORD
| nonn,mult
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 27 2007
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