|
%I #30 Aug 09 2017 21:58:51
%S 5,91,919,7795,7984,9968647168,9991319797,9999761914432,
%T 9999982446427242496
%N Numbers n such that n + DigitProd(n) = 10^(A055642(n)).
%C It is not known if this sequence is finite or infinite.
%C a(10) (if it exists) is > 10^300. - _Max Alekseyev_, Jan 15 2015
%e 919 + 9*1*9 = 1000 = 10^3. Thus 919 is a member of this sequence.
%o (PARI) DP(n)=p=1;for(i=1,#digits(n),p*=digits(n)[i]);return(p)
%o for(n=1,10^6, if((n+DP(n))==10^(#Str(n)),print(n)))
%Y Cf. A007954.
%K nonn,base,more,hard
%O 1,1
%A _Derek Orr_, May 27 2014
%E a(6)-a(9) from _Hiroaki Yamanouchi_, Jul 10 2014
|
