A136275 Similar to A137284, but considering Sum{ k = 1,2,3,... } 5^(-nk).

1, 2, 3, 5, 8, 12, 18, 26, 38, 55, 79, 114, 164, 235, 337, 483, 692, 991, 1418, 2029, 2903, 4154, 5944, 8504, 12167, 17408, 24906, 35633, 50980, 72936, 104348, 149289, 213585, 305572, 437175, 625457, 894827, 1280209, 1831566, 2620379, 3748915

Offset: 0

Author

Paolo P. Lava and Giorgio Balzarotti, Mar 19 2008

Keywords

• nonn
• base
• easy

Examples

			Start from 0;
0 + 5^(-1) = 0.2;
0.2 + 5^(-2) = 0.24 (first digit "2" is equal to the previous number's digit after the decimal point);
0.24 + 5^(-3) = 0.248 (first digits "24" are equal to the previous number's digits after the decimal point);
0.248 + 5^(-5) = 0.24832 (first digits "248" are equal to the previous number's digits after the decimal point);
etc.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Programs

Magma

[n eq 1 select 1 else Ceiling(Self(n-1)*Log(5,10)): n in [1..50]]; // Vincenzo Librandi, Jul 05 2019

Mathematica

Join[{1}, a=1; a=Table[a=Ceiling[a Log[5, 10]], {n, 40}]] (* Vincenzo Librandi, Jul 05 2019 *)

Formula

a(n) = ceiling( a(n-1)*log_5(10) ). - Max Alekseyev, May 14 2009

Extensions

Extended by Max Alekseyev, May 14 2009