1,2

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.)

See A230290.

(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

Cf. A000005, A230290-A230296.

Sequence in context: A131836 A133829 A160651 * A278317 A086454 A069360

Adjacent sequences: A230293 A230294 A230295 * A230297 A230298 A230299

nonn

N. J. A. Sloane, Oct 17 2013

approved