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A049794 a(n) = T(n,n-2), array T as in A049790. 7

%I #9 Sep 08 2022 08:44:58

%S 1,2,3,6,11,16,25,31,44,53,66,79,97,108,130,148,168,187,214,233,265,

%T 286,315,344,381,402,442,474,511,545,590,619,670,705,751,797,848,880,

%U 940,988,1041,1087,1150,1192,1263,1311,1370,1431

%N a(n) = T(n,n-2), array T as in A049790.

%H G. C. Greubel, <a href="/A049794/b049794.txt">Table of n, a(n) for n = 3..1000</a>

%p seq( `if`(n<5, n-2, add(floor((n-2)/floor((n-4)/j)), j=1..n-4)), n=3..60); # _G. C. Greubel_, Dec 10 2019

%t Table[If[n<5, n-2, Sum[Floor[(n-2)/Floor[(n-4)/j]], {j,n-4}]], {n, 3,60}] (* _G. C. Greubel_, Dec 10 2019 *)

%o (PARI) a(n) = if(n<5, n-2, sum(j=1,n-4, (n-2)\((n-4)\j)) );

%o vector(60, n, a(n+2) ) \\ _G. C. Greubel_, Dec 10 2019

%o (Magma) [n lt 5 select n-2 else (&+[Floor((n-2)/Floor((n-4)/j)): j in [1..n-4]]): n in [3..60]]; // _G. C. Greubel_, Dec 10 2019

%o (Sage)

%o def a(n):

%o if (n<5): return n-2

%o else: return sum(floor((n-2)/floor((n-4)/j)) for j in (1..n-4))

%o [a(n) for n in (3..60)] # _G. C. Greubel_, Dec 10 2019

%o (GAP)

%o a:= function(n)

%o if n<5 then return n-2;

%o else return Sum([1..n-4], j-> Int((n-2)/Int((n-4)/j)) );

%o fi; end;

%o List([3..60], n-> a(n) ); # _G. C. Greubel_, Dec 10 2019

%Y Cf. A049790, A049791, A049792, A049793, A049795, A049796.

%K nonn

%O 3,2

%A _Clark Kimberling_

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Last modified July 13 04:46 EDT 2024. Contains 374267 sequences. (Running on oeis4.)