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A195758 Lesser prime factor of n-th Blum number. 6
3, 3, 3, 3, 7, 3, 3, 7, 3, 7, 3, 3, 11, 3, 7, 3, 3, 11, 7, 3, 3, 7, 11, 3, 3, 7, 3, 19, 3, 7, 11, 3, 7, 3, 11, 3, 7, 3, 7, 19, 3, 3, 11, 3, 3, 23, 3, 7, 11, 7, 3, 11, 3, 3, 19, 3, 11, 7, 19, 11, 7, 3, 3, 7, 23, 3, 3, 7, 3, 23, 3, 19, 11, 3, 7, 3, 7, 11, 7, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) * A195759(n) = A016105(n); a(n) < A195759(n);

a(n) = A020639(A016105(n)).

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Wikipedia, Blum integer

MATHEMATICA

Take[Transpose[SortBy[{#[[1]], #[[2]], #[[1]]#[[2]]}&/@With[{c=Select[ 4*Range[ 0, 200]+3, PrimeQ]}, Subsets[c, {2}]], Last]][[1]], 90]  Harvey P. Dale, May 20 2012

PROG

(Haskell)

a195758 = a020639 . a016105

CROSSREFS

Cf. A096916.

Sequence in context: A320846 A277515 A247202 * A304684 A079084 A092323

Adjacent sequences:  A195755 A195756 A195757 * A195759 A195760 A195761

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Sep 23 2011

STATUS

approved

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Last modified May 25 11:27 EDT 2020. Contains 334592 sequences. (Running on oeis4.)