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A145745 Numbers n such that n = sigma(sum of digits of n)*sigma(product of digits of n). 0

%I

%S 1,12,6266169,6931848

%N Numbers n such that n = sigma(sum of digits of n)*sigma(product of digits of n).

%C There is no further term up to 2*10^9.

%C No further terms up to 10^26. - _Chai Wah Wu_, Nov 28 2015

%e 12 = 4*3 = sigma(1+2)*sigma(1*2).

%e 6931848 = 56*123783 = sigma(6+9+3+1+8+4+8)*sigma(6*9*3*1*8*4*8).

%t Do[h=IntegerDigits[n]; s=Apply[Plus,h];p=Apply[Times,h];If[n== DivisorSigma[1,s]*DivisorSigma[1,p],Print[n]],{n,2000000000}]

%Y Cf. A038369.

%K base,more,nonn

%O 1,2

%A _Farideh Firoozbakht_, Oct 26 2008

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Last modified October 26 18:30 EDT 2021. Contains 348268 sequences. (Running on oeis4.)