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A010693 Period 2. +0
6
2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3 (list; graph; listen)
OFFSET

0,1

COMMENT

a(n) = smallest prime divisor of n!! for n >= 2. For biggest prime divisor of n!! see A139421. - Artur Jasinski (grafix(AT)csl.pl), Apr 21 2008

LINKS

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 466

FORMULA

a(n) = 5/2 - ((-1)^n)/2.

a(n) = 2 + n mod 2 = A007395(n) + A000035(n). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Mar 23 2005

MATHEMATICA

Table[5/2 - (-1)^n/2, {n, 0, 100}] or a = {}; Do[b = First[First[FactorInteger[n!! ]]]; AppendTo[a, b], {n, 2, 1000}]; a - Artur Jasinski (grafix(AT)csl.pl), Apr 21 2008

CROSSREFS

Cf. A139421.

Adjacent sequences: A010690 A010691 A010692 this_sequence A010694 A010695 A010696

Sequence in context: A066102 A036048 A117666 this_sequence A139713 A023524 A068639

KEYWORD

nonn,easy

AUTHOR

njas

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Last modified October 7 14:39 EDT 2008. Contains 144666 sequences.


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