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A176359 Numbers with at least three 3s in their prime signature. 1
27000, 74088, 189000, 287496, 297000, 343000, 351000, 370440, 459000, 474552, 513000, 621000, 783000, 814968, 837000, 963144, 999000, 1029000, 1061208, 1107000, 1157625, 1161000, 1259496, 1269000, 1323000, 1331000, 1407672, 1431000, 1437480, 1481544, 1593000, 1647000, 1704024, 1809000, 1852200, 1917000, 1971000, 2012472, 2079000, 2133000, 2148552 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

In other words, if the canonical prime factorization of n into prime powers is Product p(i)^e(i), then e(i) = 3 for at least three values of i.

LINKS

Table of n, a(n) for n=1..41.

EXAMPLE

27000=2^3*3^3*5^3,74088=2^3*5^3*7^3,..

MATHEMATICA

f[n_]:=Count[Last/@FactorInteger[n], 3]>2; Select[Range[10!], f]

CROSSREFS

Cf. A000578, A001235, A176297, A176313, A176350, A109399.

Sequence in context: A269115 A249496 A227348 * A162144 A305728 A253485

Adjacent sequences:  A176356 A176357 A176358 * A176360 A176361 A176362

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Dec 07 2010

EXTENSIONS

Edited by Matthew Vandermast, Dec 09 2010

STATUS

approved

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Last modified June 24 13:17 EDT 2019. Contains 324325 sequences. (Running on oeis4.)