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

1,1

Comments

An analog of A245024.

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, A020639.

Sequence in context: A004261 A083118 A238204 * A245024 A264721 A136799

Adjacent sequences: A242054 A242055 A242056 * A242058 A242059 A242060

Keyword

nonn

Author

Vladimir Shevelev, Aug 13 2014

Extensions

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

Status

approved