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 A065131 Arithmetic mean of first n terms of A001414 is an integer. 0
 2, 8, 18, 26, 27, 53, 344, 539, 1221, 6869, 7271, 10753, 17742, 33289, 59688, 156649, 949350, 2291181, 3115026, 3283468, 4148225, 4493333, 18012397, 80433020, 218082214, 268274214, 639257836, 4081484513, 9373412685, 28315174578, 43438521639, 208170358834 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..32. FORMULA A025281(n)/n is integer, where A025281(n+1)=A025281(n)+A001414(n) and A001414 is sum of primes dividing n (with repetition). EXAMPLE Sum of first 18 terms of A001414 gives A025281(18)=126 which is divisible by n=18, so 18 is a term: 0+2+3+4+5+5+7+6+6+7+11+7+13+9+8+8+17+8=126=7*18, MATHEMATICA s=0; Do[s=s+lg[n]; If[IntegerQ[n/25000], Print[n]]; If[IntegerQ[s/n], Print[{n, s, s/n}]], {n, 2, 2000000}] where lg[n]=A001414(n). CROSSREFS Cf. A025281, A001414. Sequence in context: A306394 A109136 A295522 * A192157 A268810 A063581 Adjacent sequences: A065128 A065129 A065130 * A065132 A065133 A065134 KEYWORD nonn AUTHOR Labos Elemer, Oct 15 2001 EXTENSIONS a(21)-a(29) from Donovan Johnson, Apr 25 2010 a(30)-a(31) from Donovan Johnson, Jun 11 2011 a(32) from Donovan Johnson, Feb 26 2014 STATUS approved

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Last modified July 20 20:50 EDT 2024. Contains 374459 sequences. (Running on oeis4.)