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A242607 Start of a triple of consecutive squarefree numbers each of which has exactly 4 distinct prime factors. 3
27962, 37145, 39234, 42182, 50138, 51986, 58562, 62643, 64074, 83082, 84774, 89089, 95642, 120783, 123486, 133903, 134826, 146165, 149606, 153543, 159182, 166495, 170751, 176754, 177122, 178086, 178087, 179330, 180782, 203433, 207974, 211562, 212583, 214489, 219063, 219894, 219963, 225069, 228135 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..39.

Daniel C. Mayer, Define an "m-triple" to consist of three consecutive squarefree positive integers, each with exactly m prime divisors, Number Theory group on LinkedIn.com

EXAMPLE

The two squarefree numbers following a(1)=27962, 27965 and 27966, also have 4 prime divisors just as a(1).

MATHEMATICA

Transpose[Select[Partition[Select[Range[230000], SquareFreeQ], 3, 1], PrimeNu[ #] =={4, 4, 4}&]][[1]] (* Harvey P. Dale, Jul 06 2014 *)

PROG

(PARI) (back(n)=for(i=1, 2, until(issquarefree(n--), )); n); for(n=1, 9999, issquarefree(n)||next; ndk==ndm&&omega(n)==ndm&&ndk==4&&print1(back(n)", "); ndk=ndm; ndm=omega(n))

CROSSREFS

See A242605-A242608 for squarefree triples with m = 2..5 prime factors; A242621 (first terms for positive m).

Sequence in context: A206618 A233430 A220986 * A203658 A247992 A236093

Adjacent sequences:  A242604 A242605 A242606 * A242608 A242609 A242610

KEYWORD

nonn

AUTHOR

M. F. Hasler, May 18 2014

EXTENSIONS

Minor edit by Hans Havermann, Aug 19 2014

STATUS

approved

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Last modified May 16 02:09 EDT 2022. Contains 353687 sequences. (Running on oeis4.)