A087550 - OEIS

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.

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

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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 A356138

Adjacent sequences: A087547 A087548 A087549 * A087551 A087552 A087553