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A099669 Partial sums of repdigits of A002276. 7
2, 24, 246, 2468, 24690, 246912, 2469134, 24691356, 246913578, 2469135800, 24691358022, 246913580244, 2469135802466, 24691358024688, 246913580246910, 2469135802469132, 24691358024691354, 246913580246913576, 2469135802469135798, 24691358024691358020 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Matthew House, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (12,-21,10).

FORMULA

a(n) = (2/81)*(10^(n+1) - 9*n - 10). - R. Piyo (nagoya314(AT)yahoo.com), Dec 10 2004

a(n) = 12*a(n-1) - 21*a(n-2) + 10*a(n-3). - Matthew House, Jun 30 2016

G.f.: 2*x/((1 - x)^2*(1 - 10*x)). - Ilya Gutkovskiy, Jun 30 2016

EXAMPLE

2 + 22 + 222 + 2222 = a(4) = 2468.

MAPLE

A099669:=n->(2/81)*(10^(n+1) - 9*n - 10): seq(A099669(n), n=1..30); # Wesley Ivan Hurt, Apr 18 2017

MATHEMATICA

<<NumberTheory`NumberTheoryFunctions` Table[{k, Table[Apply[Plus, Table[k*(10^n-1)/9, {n, 1, m}]], {m, 1, 35}]}, {k, 1, 9}]

Table[2/9*Sum[10^i - 1, {i, n}], {n, 18}] (* Robert G. Wilson v, Nov 20 2004 *)

CROSSREFS

Cf. A057932, A002275-A002283.

Sequence in context: A252764 A215929 A132596 * A019520 A300400 A187584

Adjacent sequences:  A099666 A099667 A099668 * A099670 A099671 A099672

KEYWORD

nonn,easy

AUTHOR

Labos Elemer, Nov 17 2004

STATUS

approved

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Last modified February 21 23:41 EST 2020. Contains 332113 sequences. (Running on oeis4.)