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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 (list; graph; refs; listen; history; text; internal format)
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}]  (* Jean-François 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

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Last modified November 17 19:40 EST 2017. Contains 294834 sequences.