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A156237 Smallest hexagonal number with n distinct prime factors. 4
6, 66, 630, 7140, 103740, 1272810, 56812470, 1722580860, 48098217090, 1850186768430, 139261952960130, 17743036637876550, 741902728913225880, 21549201398378163510, 2378522762792139793830, 351206814022419685159830 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,1
COMMENTS
a(18) <= 45781615623002935783197090. - Donovan Johnson, Feb 15 2012
LINKS
Eric Weisstein's World of Mathematics, Hexagonal Numbers.
EXAMPLE
a(9) = 1722580860 = 2^2*3*5*7*11*13*23*29*43. 1722580860 is the smallest hexagonal number with 9 distinct prime factors.
MATHEMATICA
Module[{nn=167*10^5, c}, c={#, PrimeNu[#]}&/@PolygonalNumber[6, Range[nn]]; Table[ SelectFirst[ c, #[[2]]==n&], {n, 2, 12}]][[;; , 1]] (* The program generates the first 11 terms of the sequence. *) (* Harvey P. Dale, Jan 19 2024 *)
CROSSREFS
Sequence in context: A227164 A043041 A243719 * A119142 A119091 A119100
KEYWORD
nonn
AUTHOR
Donovan Johnson, Feb 07 2009
STATUS
approved

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Last modified March 4 16:59 EST 2024. Contains 370532 sequences. (Running on oeis4.)