A034051 Numbers with multiplicative digital root value 4.

4, 14, 22, 27, 39, 41, 72, 89, 93, 98, 114, 122, 127, 139, 141, 172, 189, 193, 198, 212, 217, 221, 249, 266, 271, 277, 294, 319, 333, 338, 346, 364, 379, 383, 391, 397, 411, 429, 436, 463, 492, 626, 634, 643, 662, 677, 712, 721, 727, 739, 767, 772, 776, 793

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..5000

Eric Weisstein's World of Mathematics, Multiplicative Digital Root

Index entries for 10-automatic sequences.

Maple

mdr:= proc(n) option remember;
if n < 10 then return(n) fi;
procname(convert(convert(n, base, 10), `*`))
end proc:
select(mdr=4, [$1..10^5]); # Robert Israel, Oct 19 2015

Mathematica

Select[Range@ 800, FixedPoint[Times @@ IntegerDigits@ # &, #] == 4 &] (* Michael De Vlieger, Oct 19 2015 *)

Prog

(PARI) t(n) = {while(n>9, n=prod(i=1, #n=digits(n), n[i])); n};
for(n=0, 1e4, if(t(n) == 4, print1(n", "))); \\ Altug Alkan, Oct 19 2015

Crossrefs

Cf. A031347.

Cf. A034048, A002275, A034049, A034050, A034051, A034052, A034053, A034054, A034055, A034056 (numbers having multiplicative digital roots 0-9).

Sequence in context: A165721 A197638 A051806 * A199984 A044437 A298008

Adjacent sequences: A034048 A034049 A034050 * A034052 A034053 A034054

Keyword

nonn,base,easy

Author

Patrick De Geest, Sep 15 1998

Extensions

Incorrect formula removed by Martin Renner, Oct 19 2015

Status

approved