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A036306 Composite numbers n such that digits of prime factors of n are either 1 or 6. 2
121, 671, 1331, 3721, 7271, 7381, 14641, 40321, 40931, 73271, 79981, 81191, 122771, 161051, 177221, 183271, 226981, 406321, 436921, 443531, 450241, 680821, 727771, 805981, 879791, 893101, 982771, 1016321, 1227721, 1350481, 1771561 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are a product of at least two terms of A020454. - David A. Corneth, Oct 09 2020

LINKS

David A. Corneth, Table of n, a(n) for n = 1..10000 (first 1000 terms from Alois P. Heinz)

Index entries for sequences related to prime factors

MATHEMATICA

pf16Q[n_]:=Module[{pfs=Union[Flatten[IntegerDigits/@Transpose[ FactorInteger[ n]][[1]]]]}, pfs=={1}||pfs=={1, 6}]; Select[Range[ 2*10^6], CompositeQ[#]&&pf16Q[#]&] (* Harvey P. Dale, Jul 12 2014 *)

CROSSREFS

Cf. A020454, A036302-A036325.

Sequence in context: A307798 A204034 A183885 * A014749 A262051 A048950

Adjacent sequences:  A036303 A036304 A036305 * A036307 A036308 A036309

KEYWORD

nonn,easy,base

AUTHOR

Patrick De Geest, Dec 15 1998

STATUS

approved

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Last modified January 18 14:07 EST 2021. Contains 340254 sequences. (Running on oeis4.)