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A065131
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Arithmetic mean of first n terms of A001414 is an integer.
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0
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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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FORMULA
| A025281(n)/n is integer, where A025281(n+1)=A025281(n)+A001414(n) and A001414 is sum of primes dividing n (with repetition).
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EXAMPLE
| Sum of first 18 terms of A001414 gives A025281(18)=126 which is divisible with n=18, so 18 is here: 0+2+3+4+5+5+7+6+6+7+11+7+13+9+8+8+17+8=126=7*18,
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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).
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CROSSREFS
| A025281, A001414.
Sequence in context: A171613 A109136 A137392 * A192157 A063581 A055044
Adjacent sequences: A065128 A065129 A065130 * A065132 A065133 A065134
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Oct 15 2001
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EXTENSIONS
| a(21)-a(29) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Apr 25 2010
a(30)-a(31) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Jun 11 2011
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