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A056643 Numbers n such that n | 4^n + 3^n + 2^n + 1^n. 1

%I

%S 1,2,5,6,10,25,30,50,65,125,150,190,250,625,750,978,1250,1558,1625,

%T 2405,2425,2575,3125,3750,3890,5050,6250,13250,15150,15625,18750,

%U 25250,31250,40625,71669,72010,75750,78125,93750,95950,96217,99250,115625

%N Numbers n such that n | 4^n + 3^n + 2^n + 1^n.

%F All numbers of the forms 5^k, 2*5^k & 6*5^k are in the sequence. - _Farideh Firoozbakht_, Nov 21 2006

%t Do[ If[ Mod[ PowerMod[ 4, n, n ] + PowerMod[ 3, n, n ] + PowerMod[ 2, n, n ] + 1, n ] == 0, Print[ n ] ], {n, 1, 10^6} ]

%Y Cf. A001551.

%K nonn

%O 1,2

%A _Robert G. Wilson v_, Aug 25 2000

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Last modified January 18 07:55 EST 2022. Contains 350454 sequences. (Running on oeis4.)