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A046399
Smallest squarefree palindrome with exactly n distinct prime factors.
6
1, 2, 6, 66, 858, 6006, 222222, 22444422, 244868442, 6434774346, 438024420834, 50146955964105, 2415957997595142, 495677121121776594, 22181673755737618122, 5521159517777159511255, 477552751050050157255774
OFFSET
0,2
COMMENTS
Initial terms of sequences A046392-A046398.
REFERENCES
J.-P. Delahaye, Merveilleux nombres premiers ("Amazing primes"), p. 315, Pour la Science, Paris 2000.
EXAMPLE
a(4) = 858 = 2*3*11*13.
MATHEMATICA
r[n_] := FromDigits[Reverse[IntegerDigits[n]]]; Do[k = 1; While[r[k] != k || !SquareFreeQ[k] || Length[Select[Divisors[k], PrimeQ]] != n, k++ ]; Print[k], {n, 0, 30}] (* Ryan Propper, Sep 16 2005 *)
KEYWORD
nonn,base,hard,more
AUTHOR
Patrick De Geest, Jun 15 1998
EXTENSIONS
Edited by N. J. A. Sloane, Dec 06 2008 at the suggestion of R. J. Mathar
a(10)-a(13) from Donovan Johnson, Oct 03 2011
a(14)-a(15) from David A. Corneth, Oct 03 2020
a(15) corrected by Daniel Suteu, Feb 05 2023
a(16) from Michael S. Branicky, Feb 08 2023
STATUS
approved