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A099672 Partial sums of repdigits of A002279. 1
5, 60, 615, 6170, 61725, 617280, 6172835, 61728390, 617283945, 6172839500, 61728395055, 617283950610, 6172839506165, 61728395061720, 617283950617275, 6172839506172830, 61728395061728385, 617283950617283940, 6172839506172839495, 61728395061728395050 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Colin Barker, Table of n, a(n) for n = 1..999

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

FORMULA

a(n) = (5/81)*(10^(n+1) - 9*n - 10). - R. Piyo (nagoya314(AT)yahoo.com), Dec 10 2004.

From Colin Barker, Nov 30 2017: (Start)

G.f.: 5*x / ((1 - x)^2*(1 - 10*x)).

a(n) = 12*a(n-1) - 21*a(n-2) + 10*a(n-3) for n>2.

(End)

EXAMPLE

5 + 55 + 555 + 5555 + 55555 = a(5) = 61725.

MATHEMATICA

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

Table[5/9*Sum[10^i - 1, {i, n}], {n, 18}] (* Robert G. Wilson v, Nov 20 2004 *)

Accumulate[Table[FromDigits[PadRight[{}, n, 5]], {n, 0, 20}]] (* Harvey P. Dale, Oct 05 2013 *)

PROG

(PARI) Vec(5*x / ((1 - x)^2*(1 - 10*x)) + O(x^40)) \\ Colin Barker, Nov 30 2017

CROSSREFS

Cf. A057932, A002275-A002283, A099669-A099675.

Sequence in context: A059602 A290747 A212700 * A320361 A138134 A283779

Adjacent sequences:  A099669 A099670 A099671 * A099673 A099674 A099675

KEYWORD

base,nonn,easy

AUTHOR

Labos Elemer, Nov 17 2004

STATUS

approved

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Last modified February 21 03:02 EST 2020. Contains 332086 sequences. (Running on oeis4.)