A242059 lpf_3(A242057(n)-1), where lpf_3(n) = lpf(n/3^t) (cf. A020639) such that 3^t (t>=0) is the maximal power of 3 which divides n.

1, 5, 7, 5, 1, 11, 5, 13, 5, 7, 5, 7, 5, 23, 5, 1, 5, 7, 5, 11, 5, 37, 5, 7, 5, 43, 7, 5, 47, 11, 5, 17, 5, 53, 7, 5, 13, 5, 61, 5, 7, 5, 67, 7, 5, 11, 71, 5, 13, 5, 7, 5, 1, 11, 5, 7, 5, 7, 5, 31, 5, 5, 7, 5, 103, 5, 11, 17, 5, 7, 37, 5, 113, 11, 7, 5, 13, 5

Offset

1,2

Comments

An analog of A242033.

Links

Jens Kruse Andersen, Table of n, a(n) for n = 1..10000

Mathematica

lpf[n_]:=lpf[n]=First[First[FactorInteger[n]]];
lpf3[n_]:=lpf3[n]=If[#==1, 1, lpf[#]]&[n/3^IntegerExponent[n, 3]]
Map[lpf3[#-1]&, Select[Range[4, 300, 2], lpf3[#-1]<lpf3[#-3]&]](* Peter J. C. Moses, Aug 13 2014 *)

Prog

(PARI) lpf3(n)=m=n/3^valuation(n, 3); if(m>1, factor(m)[1, 1], 1)
apply(n->lpf3(n-1), select(n->lpf3(n-1)<lpf3(n-3), vector(200, x, 2*x))) \\ Jens Kruse Andersen, Aug 19 2014

Crossrefs

Cf. A245024, A243937, A242057, A242058, A242033, A242034, A020639.

Sequence in context: A002338 A324791 A226021 * A178668 A198744 A201944

Adjacent sequences: A242056 A242057 A242058 * A242060 A242061 A242062

Keyword

nonn

Author

Vladimir Shevelev, Aug 13 2014

Extensions

More terms from Peter J. C. Moses, Aug 13 2014

Status

approved