A242058 Even numbers n for which lpf_3(n-1) > lpf_3(n-3), 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.

6, 8, 12, 14, 18, 20, 24, 30, 32, 38, 42, 44, 48, 52, 54, 58, 60, 62, 68, 72, 74, 78, 80, 84, 88, 90, 94, 98, 102, 104, 108, 110, 114, 118, 122, 124, 128, 132, 138, 140, 148, 150, 152, 158, 164, 168, 172, 174, 178, 180, 182, 188, 192, 194, 198, 200, 208, 212

Offset

1,1

Comments

An analog of A243937.

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]]
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)
select(n->lpf3(n-1)>lpf3(n-3), vector(200, x, 2*x)) \\ Jens Kruse Andersen, Aug 19 2014

Crossrefs

Cf. A245024, A243937, A242057, A020639.

Sequence in context: A287419 A315857 A243937 * A322293 A366442 A109138

Adjacent sequences: A242055 A242056 A242057 * A242059 A242060 A242061

Keyword

nonn

Author

Vladimir Shevelev, Aug 13 2014

Extensions

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

Status

approved