A099638 a[n]=A098210[n]/15.

1, 77, 7437, 741037, 74077037, 7407437037, 740741037037, 74074077037037, 7407407437037037, 740740741037037037, 74074074077037037037, 7407407407437037037037, 740740740741037037037037

Offset

1,2

Comments

Patterned-digit obtained when (1,5)-half-repdigit is divided by 15, the least such number.This simple generating rule is often[not always] applicable to provide curious digit-patterns. Thus A=1,B=7 give 111..888 numbers divided by 18 results in A003555.

Links

Table of n, a(n) for n=1..13.

Formula

a[n]=A*(((100^n-1)/9)+B*(10^n - 1)/9)/15, where A=1, B=5-A=4.

Example

n = 20: a[20] = 1111111111111111111155555555555555555555/15 = 74074074074074074077037037037037037037.

Mathematica

f[x_] := 3*((100^x-1)/9) + 4*(10^x-1)/9 Table[f[w], {w, 1, 20}]/15

Crossrefs

Cf. A098210.

Sequence in context: A361112 A210811 A107787 * A046191 A115616 A226256

Adjacent sequences: A099635 A099636 A099637 * A099639 A099640 A099641

Keyword

nonn

Author

Labos Elemer, Oct 28 2004

Status

approved