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A230296 a(n) = Sum_{i=1..n} d(72*i+1) - Sum_{i=1..n} d(18*i+1), where d(n) = A000005(n). 8
0, 2, 2, 3, 2, 2, 4, 2, 4, 6, 8, 8, 6, 4, 6, 5, 12, 8, 7, 8, 10, 12, 10, 16, 14, 12, 14, 12, 12, 12, 16, 18, 12, 14, 14, 12, 16, 20, 19, 19, 19, 26, 24, 22, 24, 24, 22, 20, 20, 20, 20, 26, 26, 24, 26, 28, 28, 22, 24, 24, 24, 30, 30, 32, 34, 36, 38, 33, 31, 30, 30, 36, 36, 35, 35, 36, 36, 36, 36, 36, 38, 38, 34, 34 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..84.

Jorge Luis Cimadevilla Villacorta, Certain inequalities associated with the divisor function, Amer. Math. Monthly, 120 (2013), 832-837. (Shows that a(n) >= 0.)

MAPLE

See A230290.

PROG

(PARI) vector(100, n, sum(i=1, n, numdiv(72*i+1)) - sum(i=1, n, numdiv(18*i+1))) \\ Michel Marcus, Oct 09 2014

CROSSREFS

Cf. A000005, A230290-A230296.

Sequence in context: A131836 A133829 A160651 * A278317 A086454 A069360

Adjacent sequences:  A230293 A230294 A230295 * A230297 A230298 A230299

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Oct 17 2013

STATUS

approved

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Last modified June 3 05:29 EDT 2020. Contains 334798 sequences. (Running on oeis4.)