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A185032 Initial term of first run of exactly n consecutive numbers with 3 distinct prime factors. 2
30, 230, 644, 1308, 2664, 6850, 10280, 39693, 44360, 48919, 218972, 534078, 2699915, 526095, 17233173, 127890362, 29138958036, 146216247221 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The number of distinct prime factors is A001221.

If any following terms exist, they are greater than 10^13.

Eggleton and MacDougall show that there are no more than 59 terms in this sequence.

a(19) <= 7523987244435061. - Donovan Johnson, Jul 08 2013

LINKS

Table of n, a(n) for n=1..18.

Roger B. Eggleton and James A. MacDougall, Consecutive integers with equally many principal divisors, Math. Mag. 81 (2008), 235-248.

R. B. Eggleton, J. S. Kimberley, and J. A. MacDougall, Principal divisor ranks of the first trillion positive integers, NOVA: The University of Newcastle’s Digital Research Repository (2009).

EXAMPLE

a(14) < a(13) because the first run of 13 consecutive integers i with A001221(i)=3 is not a maximal run.

CROSSREFS

Cf. A080569, A064709, and A185042.

Sequence in context: A156372 A064241 A080569 * A291466 A246892 A246893

Adjacent sequences:  A185029 A185030 A185031 * A185033 A185034 A185035

KEYWORD

nonn,fini

AUTHOR

R. B. Eggleton, Jason Kimberley, and J. A. MacDougall, Apr 12 2011

STATUS

approved

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Last modified September 24 07:28 EDT 2020. Contains 337317 sequences. (Running on oeis4.)