login
Powers of 9 written backwards.
4

%I #13 Jan 21 2020 20:39:06

%S 1,9,18,927,1656,94095,144135,9692874,12764034,984024783,1044876843,

%T 90695018313,184635924282,9238285681452,16945429767822,

%U 946490231198502,1481588810203581,96566699618177661,121999692536490051,9802992767171580531,10882965095456675121

%N Powers of 9 written backwards.

%H Robert Israel, <a href="/A071587/b071587.txt">Table of n, a(n) for n = 0..1046</a>

%p revdigs:= proc(n) local L;

%p L:= convert(n,base,10);

%p add(L[-i]*10^(i-1),i=1..nops(L))

%p end proc:

%p seq(revdigs(9^n),n=0..50); # _Robert Israel_, Jan 21 2020

%t IntegerReverse[9^Range[0,20]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, May 26 2018 *)

%o (PARI) for(i=1,50,n=9^i; s=ceil(log(n)/log(10)); print1(sum(i=0,s,10^(s-i-1)*(floor(n/10^i)-10*floor(n/10^(i+1)))),","))

%K easy,nonn,base

%O 0,2

%A _Benoit Cloitre_, Jun 01 2002