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 A160763 Least number having n divisors such that every sum of two or more divisors is composite. 0
 1, 3, 49, 87, 130321, 4753, 7212549413161, 285541, 7890946561, 834472284661, 174913992535407978606601, 19699251391, 23205949656945057666311162427422570380321 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS First term of A093893 to have n divisors. a(2)=3, a(3)=7^2, a(4)=3*29, a(5)=19^4, a(6)=7^2*97, a(7)=139^6, a(8)=31*61*151, a(9)=211^2*421^2, a(10)=211^4*421, a(11)=211^10, a(12)=211^2*421*1051, a(13)=2311^12, 5.92*10^20 0 && t[[a]] == 0, t[[a]] = k; Print[{a, k}]]; k += 2]; t CROSSREFS Cf. A093893, A000005. Sequence in context: A079837 A188380 A252171 * A041523 A054206 A063777 Adjacent sequences:  A160760 A160761 A160762 * A160764 A160765 A160766 KEYWORD nonn AUTHOR Robert G. Wilson v, May 25 2009, May 29 2009 EXTENSIONS Definition revised by N. J. A. Sloane, May 30 2009 Term a(9) corrected, a(10)-a(13) and more upper bounds added by Max Alekseyev and Hagen von Eitzen, May 30 2009 a(19) from M. F. Hasler, May 31 2009 Edited by Max Alekseyev, Sep 25 2009 a(1)=1 prepended by Max Alekseyev, Mar 31 2015 STATUS approved

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