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A079415 a(n) = floor(prime(n)/n) * ceiling(prime(n)/n) / 2. 1

%I #11 Sep 08 2022 08:45:08

%S 2,1,1,1,3,3,3,3,3,3,3,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,10,10,10,

%T 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,

%U 10,10,10,10,10,10,10,10,10,10,10,10,15,10,10,10,15,15,15,15,15,15,15

%N a(n) = floor(prime(n)/n) * ceiling(prime(n)/n) / 2.

%H G. C. Greubel, <a href="/A079415/b079415.txt">Table of n, a(n) for n = 1..10000</a>

%t fc[n_]:=Module[{c=Prime[n]/n},(Floor[c]Ceiling[c])/2]; Array[fc,80] (* _Harvey P. Dale_, May 20 2015 *)

%o (PARI) vector(80, n, floor(prime(n)/n)*ceil(prime(n)/n)/2) \\ _G. C. Greubel_, Jan 19 2019

%o (Magma) [Floor(NthPrime(n)/n)*Ceiling(NthPrime(n)/n)/2: n in [1..80]]; // _G. C. Greubel_, Jan 19 2019

%o (Sage) [floor(nth_prime(n)/n)*ceil(nth_prime(n)/n)/2 for n in (1..80)] # _G. C. Greubel_, Jan 19 2019

%Y Cf. A038605, A079416, A000040.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Jan 07 2003

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Last modified March 29 06:57 EDT 2024. Contains 371265 sequences. (Running on oeis4.)