A084054 5*n digit-reversed mod 5.

1, 1, 2, 2, 3, 3, 4, 4, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0

Offset

2,3

Comments

The pattern of increasing frequency of repetition of digits is clear.

Links

Table of n, a(n) for n=2..106.

Formula

From Enrique Pérez Herrero, Jun 14 2010: (Start)

a(n) = mod(floor(5*n/10^(floor(log_10(5*n)))),5), this formula comes from the modulus 5 of the first digit of 5*n.

a(10^n) = 1. (End)

Example

a(61) = 3 as, 61*5 = 305, digit reversed = 503 == 3 (mod 5).

Mathematica

A084054[n_Integer]:=Mod[FromDigits[Reverse[IntegerDigits[5*n]]], 5]; (* Enrique Pérez Herrero, Jun 14 2010 *)
(* Alternative: *)
A084054[n_Integer]:=Mod[Floor[5*n/10^Floor[Log[10, 5*n]]], 5] (* Enrique Pérez Herrero, Jun 14 2010 *)

Crossrefs

Cf. A084052, A084053, A084055, A084339, A084340, A084341.

Sequence in context: A117171 A325356 A304706 * A106747 A335979 A083447

Adjacent sequences: A084051 A084052 A084053 * A084055 A084056 A084057

Keyword

base,easy,nonn

Author

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 26 2003

Extensions

More terms from Ray Chandler, May 27 2003

Status

approved