

A086560


Start of first run of n successive numbers in which ith number has exactly i distinct prime divisors for i = 1..n.


7




OFFSET

1,1


REFERENCES

J.M. De Koninck, Ces nombres qui nous fascinent, Entry 64, p. 23, Ellipses, Paris 2008.


LINKS

Table of n, a(n) for n=1..8.


EXAMPLE

a(3) = 64, as 64 has 1, 65 has 2 and 66 has 3 prime divisors: 64 = 2^6, 65 = 5*13 and 66 = 2*3*11


CROSSREFS

Cf. A072875.
Sequence in context: A012949 A076630 A270389 * A305292 A268211 A246280
Adjacent sequences: A086557 A086558 A086559 * A086561 A086562 A086563


KEYWORD

more,nonn


AUTHOR

Amarnath Murthy, Aug 30 2003


EXTENSIONS

More terms from Don Reble, Sep 13 2003
a(7) from Donovan Johnson, Mar 06 2008
a(8) from Donovan Johnson, Jul 19 2011


STATUS

approved



