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%I #37 Feb 13 2017 20:21:11
%S 5,15,35,51,53,57,75,115,135,151,153,157,175,315,351,355,359,395,511,
%T 513,517,531,535,539,553,557,571,575,579,593,597,715,751,755,759,795,
%U 935,953,957,975,1115,1135,1151,1153,1157,1175,1315,1351,1355,1359,1395
%N Numbers with multiplicative digital root value 5.
%C All digits of a(n) must be odd. - _Robert Israel_, Oct 19 2015
%H Robert Israel, <a href="/A034052/b034052.txt">Table of n, a(n) for n = 1..10000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/MultiplicativeDigitalRoot.html">Multiplicative Digital Root</a>
%H <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>.
%p mdr:= proc(n) option remember;
%p if n < 10 then return(n) fi;
%p procname(convert(convert(n,base,10),`*`))
%p end proc:
%p select(mdr=5, [$1..10^5]); # _Robert Israel_, Oct 19 2015
%t mrQ[n_]:=NestWhile[Times@@IntegerDigits[#]&,n,#>10&]==5; Select[Range[1395],mrQ[#]&] (* _Jayanta Basu_, May 30 2013 *)
%o (PARI) t(n) = {while(n>9, n=prod(i=1, #n=digits(n), n[i])); n};
%o for(n=0, 1e4, if(t(n) == 5, print1(n", "))); \\ _Altug Alkan_, Oct 19 2015
%Y Cf. A031347.
%Y Cf. A034048, A002275, A034049, A034050, A034051, A034052, A034053, A034054, A034055, A034056 (numbers having multiplicative digital roots 0-9).
%K nonn,base,easy
%O 1,1
%A _Patrick De Geest_, Sep 15 1998
%E Incorrect formula removed by _Martin Renner_, Oct 19 2015
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