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 A230293 a(n) = Sum_{i=1..n} d(8*i+1) - Sum_{i=1..n} d(4*i+1), where d(n) = A000005(n). 4
 1, 0, 1, 3, 1, 1, 3, 3, 3, 6, 2, 1, 7, 5, 6, 6, 4, 6, 8, 7, 6, 8, 8, 8, 10, 6, 8, 15, 11, 10, 10, 8, 8, 14, 12, 11, 17, 15, 15, 15, 11, 10, 16, 14, 15, 17, 13, 19, 21, 19, 17, 17, 19, 17, 22, 15, 15, 21, 21, 23, 21, 21, 21, 27, 23, 22, 24, 20, 22, 28, 22, 21, 31, 25, 23, 27, 25, 28, 30, 28, 26, 28, 30, 30, 30, 26, 28 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS Jorge Luis Cimadevilla Villacorta, Certain inequalities associated with the divisor function, Amer. Math. Monthly, 120 (2013), 832-837. (Shows that a(n) >= 0.) FORMULA a(n) = A230476(n) - A230294(n). - Jonathan Sondow, Oct 20 2013 MAPLE See A230290. PROG (PARI) vector(100, n, sum(i=1, n, numdiv(8*i+1)) - sum(i=1, n, numdiv(4*i+1))) \\ Michel Marcus, Oct 09 2014 CROSSREFS Cf. A000005, A230290-A230296, A230476. Sequence in context: A035666 A060592 A080426 * A133116 A059959 A192812 Adjacent sequences:  A230290 A230291 A230292 * A230294 A230295 A230296 KEYWORD nonn AUTHOR N. J. A. Sloane, Oct 17 2013 STATUS approved

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Last modified May 25 19:30 EDT 2020. Contains 334595 sequences. (Running on oeis4.)