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A087550 a(n) = smallest k such that for each r, 2 <= r <= n, there exists a distinct s, n < s <= k, with the same prime signature as r. 0
3, 7, 9, 13, 13, 19, 27, 49, 49, 49, 49, 49, 49, 49, 81, 81, 81, 81, 81, 81, 81, 81, 81, 169, 169, 343, 343, 343, 343, 343, 343, 343, 343, 343, 343, 343, 343, 343, 343, 343, 343, 343, 343, 343, 343, 343, 343, 361, 361, 361, 361, 361, 361, 361, 361, 361, 361, 361 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Table of n, a(n) for n=2..59.

FORMULA

For sufficiently large n, a(n) = 7^floor(log(n)/log(3)) because log(prime(2m))/log(prime(m)) is largest for m = 2. - David Wasserman, Jun 03 2005

EXAMPLE

a(7) = 19 and For numbers ( 2,3,4,5,6,7) we have the set of numbers ( 11,13,9,17,10,19) with matching prime signatures.

CROSSREFS

Sequence in context: A353103 A087064 A189561 * A235387 A285144 A047241

Adjacent sequences:  A087547 A087548 A087549 * A087551 A087552 A087553

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Sep 13 2003

EXTENSIONS

More terms from David Wasserman, Jun 03 2005

STATUS

approved

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Last modified July 4 03:54 EDT 2022. Contains 355063 sequences. (Running on oeis4.)