A185032 Initial term of first run of exactly n consecutive numbers with 3 distinct prime factors.

30, 230, 644, 1308, 2664, 6850, 10280, 39693, 44360, 48919, 218972, 534078, 2699915, 526095, 17233173, 127890362, 29138958036, 146216247221

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