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

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]));
A179953(n) = { my(q = A006530(n), m = q, k=1); while(m < n, m *= q; k++); k; }; \\ Antti Karttunen, Oct 20 2017

Crossrefs

Cf. A006530.

Sequence in context: A366989 A318322 A122810 * A277013 A305822 A326190

Adjacent sequences: A179950 A179951 A179952 * A179954 A179955 A179956

Keyword

easy,nonn

Author

Dylan Hamilton, Aug 03 2010

Extensions

a(1) = 1 prepended and definition rewritten by Antti Karttunen, Oct 20 2017

Status

approved