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 A091414 Least number that is the sum of n positive n-th powers in at least 2 ways. 2
 50, 251, 259, 4097, 570947, 73310705, 647282661, 79327628290, 1077347903894, 1761813250036143, 2343908545594901 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS From Donovan Johnson, Sep 14 2008: (Start) a(11) = 2^11 + 2^11 + 2^11 + 2^11 + 8^11 + 10^11 + 10^11 + 15^11 + 22^11 + 22^11 + 22^11 = 3^11 + 5^11 + 5^11 + 5^11 + 6^11 + 9^11 + 11^11 + 12^11 + 17^11 + 20^11 + 24^11. a(12) = 2^12 + 2^12 + 2^12 + 2^12 + 2^12 + 2^12 + 2^12 + 9^12 + 9^12 + 9^12 + 15^12 + 19^12 = 3^12 + 5^12 + 5^12 + 10^12 + 10^12 + 10^12 + 10^12 + 12^12 + 12^12 + 17^12 + 17^12 + 18^12. a(13) > 876*10^15. a(14) > 799*10^15. a(15) > 115*10^16. (End) LINKS FORMULA a(n) <= A230477(n) for n > 1, with equality at least for n = 2 and inequality at least for n = 3, 4, 5. - Jonathan Sondow, Oct 24 2013 EXAMPLE a(3) = 251 because 251 = 1^3 + 5^3 + 5^3 = 2^3 + 3^3 + 6^3 and it is the smallest number that can be represented two ways as the sum of three third powers. CROSSREFS a(2) = A048610(2), a(3) = A008917(1), a(4) = A185673(2). - Jonathan Sondow, Oct 24 2013 Cf. A230561, A230477. Sequence in context: A197971 A235567 A091883 * A186123 A220864 A205355 Adjacent sequences:  A091411 A091412 A091413 * A091415 A091416 A091417 KEYWORD more,nonn AUTHOR Gabriel Cunningham (gcasey(AT)mit.edu), Mar 02 2004 EXTENSIONS More terms from David Wasserman, Mar 09 2006 a(11)-a(12) from Donovan Johnson, Sep 14 2008 Definition shortened by Jonathan Sondow, Oct 24 2013 STATUS approved

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Last modified January 22 07:31 EST 2022. Contains 350481 sequences. (Running on oeis4.)