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A281787 a(n) = sum of all numbers between 1 and 10^n that are divisible by 3 or 5. 1
23, 2318, 233168, 23331668, 2333316668, 233333166668, 23333331666668, 2333333316666668, 233333333166666668, 23333333331666666668, 2333333333316666666668, 233333333333166666666668, 23333333333331666666666668, 2333333333333316666666666668 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Jerry Polfer, Table of n, a(n) for n = 1..500

Project Euler, Problem 1: Multiples of 3 and 5

Index entries for linear recurrences with constant coefficients, signature (111,-1110,1000).

FORMULA

G.f.: -x*(23-235*x+1400*x^2)/((x-1)*(100*x-1)*(10*x-1)). - Alois P. Heinz, Jan 30 2017

a(n) = (7/30)*100^n - (1/6)*10^n + 4/3. - Robert Israel, Jan 31 2017

EXAMPLE

For n = 1, a(1) = 3 + 5 + 6 + 9 = 23.

PROG

(PARI) Vec(-x*(23-235*x+1400*x^2)/((x-1)*(100*x-1)*(10*x-1)) + O(x^15)) \\ Felix Fröhlich, Jan 30 2017

CROSSREFS

Sequence in context: A263462 A138735 A220653 * A132937 A068655 A336170

Adjacent sequences:  A281784 A281785 A281786 * A281788 A281789 A281790

KEYWORD

nonn,easy

AUTHOR

Jerry Polfer, Jan 29 2017

STATUS

approved

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Last modified May 14 03:00 EDT 2021. Contains 343872 sequences. (Running on oeis4.)