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A100416 Numbers n such that sum of the proper divisors of n is equal to d_1!+d_2!+...+d_k!, where d_1 d_2 ... d_k is the decimal expansion of n. 2

%I #8 Oct 11 2018 15:31:04

%S 561653,606061,1649345,2631227,5657101,25376713,33805243,38747603,

%T 68760599,77773043,80404183,101695597,124781123,125348239,142692929,

%U 152212087,177464929,184416409,192144907,200781041,238715647,241253839

%N Numbers n such that sum of the proper divisors of n is equal to d_1!+d_2!+...+d_k!, where d_1 d_2 ... d_k is the decimal expansion of n.

%e 38747603 is in the sequence because {1,769,50387} is the set of proper

%e divisors of 38747603 and 3!+8!+7!+4!+7!+6!+0!+3!=1+769+50387.

%t Do[h = IntegerDigits[n]; l = Length[h]; If[DivisorSigma[1, n] - n == Sum[h[[k]]!, {k, l}], Print[n]], {n, 60000000}]

%t Select[Range[2413*10^5],Total[Most[Divisors[#]]]==Total[ IntegerDigits[ #]!]&] (* _Harvey P. Dale_, Oct 11 2018 *)

%Y Cf. A101697.

%K base,nonn

%O 1,1

%A _Farideh Firoozbakht_, Dec 12 2004

%E a(9)-a(22) from _Donovan Johnson_, Dec 07 2008

%E Comment deleted by _Harvey P. Dale_, Oct 11 2018

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Last modified April 16 04:02 EDT 2024. Contains 371696 sequences. (Running on oeis4.)