cp's OEIS Frontend

A028900 Map n = Sum c_i 10^i to a(n) = Sum c_i 5^i.

%I A028900 #11 Jul 08 2025 18:54:53
%S A028900 0,1,2,3,4,5,6,7,8,9,5,6,7,8,9,10,11,12,13,14,10,11,12,13,14,15,16,17,
%T A028900 18,19,15,16,17,18,19,20,21,22,23,24,20,21,22,23,24,25,26,27,28,29,25,
%U A028900 26,27,28,29,30,31,32,33,34,30,31,32,33,34,35,36,37,38,39,35,36,37,38,39
%N A028900 Map n = Sum c_i 10^i to a(n) = Sum c_i 5^i.
%H A028900 Robert Israel, <a href="/A028900/b028900.txt">Table of n, a(n) for n = 0..10000</a>
%p A028900 f:= proc(n) local L,i;
%p A028900   L:= convert(n,base,10);
%p A028900   add(L[i]*5^(i-1),i=1..nops(L))
%p A028900 end proc:
%p A028900 map(f, [$1..100]); # _Robert Israel_, Jan 14 2021
%K A028900 nonn,base,look
%O A028900 0,3
%A A028900 _N. J. A. Sloane_
%E A028900 More terms from _Erich Friedman_.