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

1, 12, 6266169, 6931848

Offset: 1

Author

Farideh Firoozbakht, Oct 26 2008

Keywords

• base
• more
• nonn

Comments

No further terms up to 10^26. - Chai Wah Wu, Nov 28 2015

No other terms below 10^100. The sequence is likely finite and complete. - Max Alekseyev, Sep 05 2023

Examples

			12 = 4*3 = sigma(1+2)*sigma(1*2).
6931848 = 56*123783 = sigma(6+9+3+1+8+4+8)*sigma(6*9*3*1*8*4*8).
		

Crossrefs

Cf. A038369.

Programs

Mathematica

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