A123873 - OEIS

%I #14 Aug 08 2023 12:18:04

%S 4,6,26,126,3126,15625001,156250000000001,

%T 15625000000000000000000000001,

%U 156250000000000000000000000000000000000000000000000000001,156250000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001

%N Similar to A123872 but with a(0)=4 as seed.

%D G. Balzarotti and P. P. Lava, Le sequenze di numeri interi, Hoepli, 2008, p. 99.

%e a(0)=4;

%e a(1)=6 because 4*6 = 24;

%e a(2)=26 because 24*26 = 624;

%e a(3)=126 because 624*126 = 78624;

%e a(4)=3126 because 78624*3126 = 245778624;

%e a(5)=15625001 because 245778624*15625001 = 3840291245778624.

%p P:=proc(q,h) local a,b,k,n; a:=h; b:=ilog10(a)+1; print(h);

%p for k from 1 to 10 do for n from 2 to q do

%p if ((a*n) mod 10^b)=a then print(n); a:=a*n; b:=ilog10(a)+1;

%p break; fi; od; od; end: P(10^9,4);

%K nonn,base

%O 0,1

%A _Paolo P. Lava_ and _Giorgio Balzarotti_, Oct 16 2006, Oct 24 2006

%E More terms from _Bert Dobbelaere_, Aug 08 2023