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 A274774 Least k such that sigma(k*n)/tau(k*n) = sigma(k*n+1)/tau(k*n+1), or 0 if no such k exists. 0
 5, 7, 895, 1363, 1, 3353, 2, 2589, 1007, 10341, 1265, 1726, 7, 1, 179, 6634, 10052, 5745, 86, 53389, 958, 12165, 58, 863, 649, 250017, 2395, 6103, 46, 3447, 2714, 3317, 8110, 5026, 22653, 2812637, 94, 43, 16795, 58069, 61693, 479, 38, 52790, 1437, 29, 74, 2027510, 122367, 70545 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Corresponding averages are 3, 6, 540, 840, 3, 2880, 6, 3240, 1170, 8640, 1596, 3240, 28, 6, 540, 9072, 15120, 8640, 330, 55440, 2880, 21924, 270, 3240, 1860, 875070, 7200, ... LINKS EXAMPLE a(13) = 7 because sigma(7*13)/tau(7*13) = sigma(7*13+1)/tau(7*13+1). MATHEMATICA a[n_] := Block[{k=1}, While[! Equal @@ (DivisorSigma[1, n*k + {0, 1}] / DivisorSigma[ 0, n*k + {0, 1}]), k++]; k]; Array[a, 20] (* Giovanni Resta, Jul 28 2016 *) PROG (PARI) a(n) = {my(k=1); while (sigma(k*n)/numdiv(k*n) != sigma(k*n+1)/numdiv(k*n+1), k++); k; } CROSSREFS Cf. A238380. Sequence in context: A083687 A101829 A056252 * A176599 A309409 A291687 Adjacent sequences:  A274771 A274772 A274773 * A274775 A274776 A274777 KEYWORD nonn AUTHOR Altug Alkan, Jul 28 2016 STATUS approved

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Last modified September 24 03:26 EDT 2021. Contains 347623 sequences. (Running on oeis4.)