id:A068211 - OEIS Search Results

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Largest prime factor of Euler Phi of n.

+0
10

2, 2, 2, 2, 3, 2, 3, 2, 5, 2, 3, 3, 2, 2, 2, 3, 3, 2, 3, 5, 11, 2, 5, 3, 3, 3, 7, 2, 5, 2, 5, 2, 3, 3, 3, 3, 3, 2, 5, 3, 7, 5, 3, 11, 23, 2, 7, 5, 2, 3, 13, 3, 5, 3, 3, 7, 29, 2, 5, 5, 3, 2, 3, 5, 11, 2, 11, 3, 7, 3, 3, 3, 5, 3, 5, 3, 13, 2, 3, 5, 41, 3, 2, 7, 7, 5, 11, 3, 3, 11, 5, 23, 3, 2, 3, 7, 5, 5 (list; graph; listen)

	OFFSET	`3,1`
	COMMENT	`Smallest numbers m, such that largest prime-factor of Phi[m] is prime(n), the n-th prime is also a prime number and identical to n-th term of A035095: Min[x; A068211(x)=prime(n)]=A035095(n); e.g. Phi[a(7)]=Phi[103]=2.3.17 of which 17=p(7) is the largest prime-factor.`
	FORMULA	`a(n)=A006530[A000010(n)]`
	EXAMPLE	`n=46, Phi[46]=2.2.11, a(46)=11`
	MATHEMATICA	`ffi[x_] := Flatten[FactorInteger[x]]; lf[x_] := Length[FactorInteger[x]]; ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}]; Table[Max[ba[EulerPhi[w]]], {w, 1, 256}]`
	CROSSREFS	`Cf. A006530, A000010.` `Cf. A035095, A035096.` `Adjacent sequences: A068208 A068209 A068210 this_sequence A068212 A068213 A068214` `Sequence in context: A078120 A057525 A139325 this_sequence A089050 A125173 A054725`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), Feb 21 2002`

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Last modified October 5 16:50 EDT 2008. Contains 144613 sequences.

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