A179953 - OEIS

A179953

a(n) is the least exponent k such that q^k >= n, where q is the greatest prime factor of n (= A006530(n)); a(1) = 1 by convention.

1, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 3, 1, 2, 2, 4, 1, 3, 1, 2, 2, 2, 1, 3, 2, 2, 3, 2, 1, 3, 1, 5, 2, 2, 2, 4, 1, 2, 2, 3, 1, 2, 1, 2, 3, 2, 1, 4, 2, 3, 2, 2, 1, 4, 2, 3, 2, 2, 1, 3, 1, 2, 3, 6, 2, 2, 1, 2, 2, 3, 1, 4, 1, 2, 3, 2, 2, 2, 1, 3, 4, 2, 1, 3, 2, 2, 2, 2, 1, 3, 2, 2, 2, 2, 2, 5, 1, 3, 2, 3, 1, 2, 1, 2, 3, 2

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OFFSET

1,4

COMMENTS

Previous name was: a(n) is the least integer such that the greatest prime factor of n is greater than or equal to its a(n)th root.

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..16384

MATHEMATICA

Table[n = 1; m = Max[FactorInteger[x][[All, 1]]]; While[x^(1/n) > m, ++n]; n, {x, START, END}]

PROG

(PARI)

A006530(n) = if(1==n, n, vecmax(factor(n)[, 1]));