OFFSET
1,2
COMMENTS
Contains A003598. In general n=p^iq^i => n|Sum[k=1..2p, k^n], where p, q=2p+1 prime (see Meyer ref).
LINKS
MATHEMATICA
Do[ If[ Mod[ PowerMod[ 10, n, n ] + PowerMod[ 9, n, n ] + PowerMod[ 8, n, n ] + PowerMod[ 7, n, n ] + PowerMod[ 6, n, n ] + PowerMod[ 5, n, n ] + PowerMod[ 4, n, n ] + PowerMod[ 3, n, n ] + PowerMod[ 2, n, n ] + 1, n ] == 0, Print[ n ] ], {n, 1, 10^6} ]
Select[Range[700000], Divisible[Total[Range[10]^#], #]&] (* Harvey P. Dale, Nov 24 2014 *)
Select[Range[700000], Mod[Total[PowerMod[Range[10], #, #]], #]==0&] (* Harvey P. Dale, Feb 23 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Aug 25 2000
STATUS
approved