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 A128981 Numbers n such that n divides Sum_{k=1..n} k^k = A001923(n). 3
 1, 4, 17, 19, 148, 1577, 3564, 4388, 5873, 6639, 8579, 62500, 376636, 792949, 996044, 1174065, 3333551, 5179004, 7516003 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(20) > 10^7. - Hiroaki Yamanouchi, Aug 25 2015 LINKS MAPLE ListA128981:= proc(q) local a, n; a:=0; for n from 1 to q do a:=a+n^n; if a mod n=0 then print(n); fi; od; end: ListA128981(10^7); # Paolo P. Lava, Jul 10 2013 a:=0: for n from 1 to 2000 do     a:=a+n^n:     if a mod n=0 then         print(n);     fi; od: # Revised program from R. J. Mathar, Jun 18 2015 MATHEMATICA f=0; Do[ f=f+k^k; If[ IntegerQ[f/k], Print[k] ], {k, 1, 6639} ] PROG (PARI) for(n=1, 10^4, s=sum(i=1, n, Mod(i, n)^i); if(!Mod(s, n), print1(n, ", "))) \\ Derek Orr, Jun 18 2015 CROSSREFS Cf. A062970, A001923. Sequence in context: A138268 A031444 A031033 * A212748 A032828 A193379 Adjacent sequences:  A128978 A128979 A128980 * A128982 A128983 A128984 KEYWORD hard,more,nonn AUTHOR Alexander Adamchuk, Apr 29 2007 EXTENSIONS a(11) and a(12) from Jon E. Schoenfield, May 09 2007 a(13) = 376636 from Alexander Adamchuk, May 03 2010 a(14)-a(16) from Lars Blomberg, May 10 2011 a(17) from Giovanni Resta, Jul 13 2015 a(18)-a(19) from Hiroaki Yamanouchi, Aug 25 2015 STATUS approved

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Last modified October 15 04:33 EDT 2019. Contains 328026 sequences. (Running on oeis4.)