A242057 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.

10, 16, 22, 26, 28, 34, 36, 40, 46, 50, 56, 64, 66, 70, 76, 82, 86, 92, 96, 100, 106, 112, 116, 120, 126, 130, 134, 136, 142, 144, 146, 154, 156, 160, 162, 166, 170, 176, 184, 186, 190, 196, 202, 204, 206, 210, 214, 216, 222, 226, 232, 236, 244, 254, 256, 260

Offset: 1

Author

Vladimir Shevelev, Aug 13 2014

Keywords

• nonn

Comments

An analog of A245024.

Links

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

Crossrefs

Cf. A245024, A243937, A020639.

Programs

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]Peter J. C. Moses, Aug 13 2014 *)

PARI

lpf3(n)=m=n/3^valuation(n, 3); if(m>1, factor(m)[1,1], 1)
select(n->lpf3(n-1)Jens Kruse Andersen, Aug 19 2014

Extensions

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