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A099638 a[n]=A098210[n]/15. 1
1, 77, 7437, 741037, 74077037, 7407437037, 740741037037, 74074077037037, 7407407437037037, 740740741037037037, 74074074077037037037, 7407407407437037037037, 740740740741037037037037 (list; graph; refs; listen; history; text; internal format)
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: A180837 A210811 A107787 * A046191 A115616 A226256

Adjacent sequences:  A099635 A099636 A099637 * A099639 A099640 A099641

KEYWORD

nonn

AUTHOR

Labos Elemer, Oct 28 2004

STATUS

approved

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Last modified September 19 21:42 EDT 2020. Contains 337184 sequences. (Running on oeis4.)