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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. 6
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 4 09:03 EDT 2020. Contains 336201 sequences. (Running on oeis4.)