

A033677


Smallest divisor of n >= sqrt(n).


38



1, 2, 3, 2, 5, 3, 7, 4, 3, 5, 11, 4, 13, 7, 5, 4, 17, 6, 19, 5, 7, 11, 23, 6, 5, 13, 9, 7, 29, 6, 31, 8, 11, 17, 7, 6, 37, 19, 13, 8, 41, 7, 43, 11, 9, 23, 47, 8, 7, 10, 17, 13, 53, 9, 11, 8, 19, 29, 59, 10, 61, 31, 9, 8, 13, 11, 67, 17, 23, 10, 71, 9, 73, 37, 15, 19, 11, 13, 79, 10
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OFFSET

1,2


COMMENTS

a(n) is the smallest k such that n appears in the k X k multiplication table and A027424(k) is the number of n with a(n) <= k.


REFERENCES

G. Tenenbaum, pp. 268ff of R. L. Graham et al., eds., Mathematics of Paul Erdős I.


LINKS

T. D. Noe, Table of n, a(n) for n=1..10000


FORMULA

a(n) = n/A033676(n).
a(n) = A162348(2n).  Daniel Forgues, Sep 29 2014


MAPLE

A033677 := proc(n)
n/A033676(n) ;
end proc:


MATHEMATICA

Table[Select[Divisors[n], # >= Sqrt[n] &, 1] // First, {n, 80}] (* JeanFrançois Alcover, Apr 01 2011 *)


PROG

(PARI) A033677(n) = {local(d); d=divisors(n); d[length(d)\2+1]} \\ Michael B. Porter, Feb 26 2010
(Haskell)
a033677 n = head $
dropWhile ((< n) . (^ 2)) [d  d < [1..n], mod n d == 0]
 Reinhard Zumkeller, Oct 20 2011


CROSSREFS

Cf. A027424, A056737, A219695.
Sequence in context: A165500 A072505 A095163 * A116548 A117818 A073890
Adjacent sequences: A033674 A033675 A033676 * A033678 A033679 A033680


KEYWORD

nonn,easy,nice


AUTHOR

N. J. A. Sloane


STATUS

approved



