|
%I #22 Jan 13 2019 19:39:06
%S 24,200,208,216,224,232,240,248,256,264,272,280,288,296,324,351,378,
%T 448,500,648,2000,2008,2016,2024,2032,2040,2048,2056,2064,2072,2080,
%U 2088,2096,2104,2112,2120,2128,2136,2144,2152,2160,2168,2176,2184,2192,2200,2208
%N Numbers divisible by their first digit cubed (excluding those whose first digit is 1).
%C Numbers where floor(n/10^floor(log(n)))^3 | n.
%H Christian N. K. Anderson, <a href="/A225296/b225296.txt">Table of n, a(n) for n = 1..10000</a>
%H Christian N. K. Anderson, <a href="/A225296/a225296_1.gif">Ulam Spiral</a> of first 10000 terms.
%e 448 is divisible by 4^3.
%t dfdcQ[n_]:=Module[{fidn=IntegerDigits[n][[1]]},fidn!=1&&Divisible[ n,fidn^3]]; Select[Range[2500],dfdcQ] (* _Harvey P. Dale_, Jan 13 2019 *)
%o (R) x=0; y=rep(0,1000); len=0
%o firstdig<-function(x) as.numeric(substr(as.character(x),1,1))
%o isint<-function(x) x==as.integer(x)
%o while(len<1000) if((fd=firstdig((x=x+1)))>1) if(isint(x/fd^3)) y[(len=len+1)]=x
%Y Cf. A132359, A034709, A034837, A005349, A007602, A034838.
%K nonn,base
%O 1,1
%A _Kevin L. Schwartz_ and _Christian N. K. Anderson_, May 04 2013
|
