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A328448
Smallest number whose divisors > 1 have a longest run of length n, and 0 if none exists.
6
2, 6, 12, 504, 60, 420, 840, 4084080, 2520, 21162960, 27720, 2059318800, 0, 360360, 720720, 8494326640800, 12252240, 281206918792800, 0, 0, 232792560, 409547311252279200, 5354228880, 619808900849199341280, 26771144400, 54749786241679275146400, 80313433200, 5663770990518545704800
OFFSET
1,1
EXAMPLE
The runs of divisors of 504 (greater than 1) are {{2,3,4},{6,7,8,9},{12},{14},{18},{21},{24},{28},{36},{42},{56},{63},{72},{84},{126},{168},{252},{504}}, the longest of which has length 4, and 504 is the smallest number with this property, so a(4) = 504.
CROSSREFS
The version that looks at all divisors (including 1) is A328449.
The longest run of divisors of n greater than 1 has length A328457.
Numbers whose divisors > 1 have no non-singleton runs are A088725.
The number of successive pairs of divisors of n is A129308(n).
The Heinz number of the multiset of run-lengths of divisors of n is A328166(n).
Sequence in context: A058046 A298410 A367314 * A074180 A126293 A007668
KEYWORD
nonn
AUTHOR
Gus Wiseman, Oct 16 2019
EXTENSIONS
Data corrected and extended by Giovanni Resta, Oct 18 2019
STATUS
approved