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A309124 a(n) = n - 3 * floor(n/3) + 5 * floor(n/5) - 7 * floor(n/7) + ... 0
1, 2, 0, 1, 7, 5, -1, 0, 7, 13, 3, 1, 15, 9, -3, -2, 16, 23, 5, 11, 23, 13, -9, -11, 20, 34, 14, 8, 38, 26, -4, -3, 17, 35, -1, 6, 44, 26, -2, 4, 46, 58, 16, 6, 48, 26, -20, -22, 21, 52, 16, 30, 84, 64, 4, -2, 34, 64, 6, -6, 56, 26, -16, -15, 69, 89, 23, 41, 85, 49, -21, -14, 60, 98, 36 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Partial sums of A050457.

LINKS

Table of n, a(n) for n=1..75.

FORMULA

G.f.: (1/(1 - x)) * Sum_{k>=1} (-1)^(k+1) * (2*k - 1) * x^(2*k-1)/(1 - x^(2*k-1)).

MATHEMATICA

Table[Sum[(-1)^(k + 1) (2 k - 1) Floor[n/(2 k - 1)], {k, 1, n}], {n, 1, 75}]

nmax = 75; CoefficientList[Series[1/(1 - x) Sum[(-1)^(k + 1) (2 k - 1) x^(2 k - 1)/(1 - x^(2 k - 1)), {k, 1, nmax}], {x, 0, nmax}], x] // Rest

CROSSREFS

Cf. A014200, A024919, A050457, A078471.

Sequence in context: A325754 A154974 A291820 * A078341 A199459 A316649

Adjacent sequences:  A309121 A309122 A309123 * A309125 A309126 A309127

KEYWORD

sign

AUTHOR

Ilya Gutkovskiy, Jul 13 2019

STATUS

approved

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Last modified August 6 15:50 EDT 2020. Contains 336255 sequences. (Running on oeis4.)