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%I #13 Jul 17 2016 12:51:42
%S 1,2,3,6,9,14,23,48,82,55,250,100,469,2213,2232,296,6623,489,29495,
%T 89362,35815,1254,259171,411355,176134,952660,3819125
%N First differences of A115855.
%C By definition of A115855, a(n+1) is the number of ways 1 can be written as sum of distinct positive fractions having no denominator larger than n, and at least one equal to n (in its reduced form). - _M. F. Hasler_, Jul 14 2016
%F a(n) = A115855(n+1) - A115855(n);
%F a(A000040(n)-1) = A000041(A000040(n))-1.
%t Table[Length@ Select[Flatten[Map[IntegerPartitions[1, {#}, Rest@ Union[Flatten@ TensorProduct[#, 1/#] &@ Range@ n /. {_Integer -> 0, k_ /; k > 1 -> 0}]] &, Range@ n], 1], Total@ # == 1 && MemberQ[Union@ Denominator@ #, n] &], {n, 2, 25}] (* _Michael De Vlieger_, Jul 15 2016 *)
%Y Cf. A116085.
%K nonn,more
%O 1,2
%A _Reinhard Zumkeller_, Feb 01 2006
%E More terms from _Michael De Vlieger_, Jul 15 2016
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