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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

Table of n, a(n) for n=1..19.

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 April 30 16:28 EDT 2017. Contains 285670 sequences.