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A071311 Squarefree numbers n with largest prime factor = floor(sqrt(n)). 0
30, 182, 195, 399, 870, 1023, 1406, 1443, 1722, 2915, 3782, 4623, 5402, 7055, 8099, 10302, 10815, 11990, 12099, 12882, 12995, 16383, 17423, 18906, 19599, 24806, 24963, 26895, 30102, 32942, 33123, 37442, 37635, 39999, 44943, 52670, 52899 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If n = p(1)*p(2)*...p(r) is in the sequence, where p(r) is the largest prime factor, then p(1)*p(2)*...*p(r-1) - p(r) = 1 or 2

LINKS

Table of n, a(n) for n=1..37.

EXAMPLE

1023 = 3.11.31 and sqrt(1023)=31.98437... hence 1023 is in the sequence

PROG

(PARI) for(n=2, 100000, if(issquarefree(n)*component(component(factor(n), 1), omega(n))==floor(sqrt(n)), print1(n, ", ")))

CROSSREFS

Cf. A071835.

Sequence in context: A281999 A156318 A042758 * A337494 A265037 A249001

Adjacent sequences:  A071308 A071309 A071310 * A071312 A071313 A071314

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Jun 11 2002

STATUS

approved

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Last modified July 25 09:49 EDT 2021. Contains 346289 sequences. (Running on oeis4.)