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a(n) = (prime(n)^5 - prime(n))/2.
3

%I #15 Sep 08 2022 08:45:33

%S 15,120,1560,8400,80520,185640,709920,1238040,3218160,10255560,

%T 14314560,34671960,57928080,73504200,114672480,209097720,357462120,

%U 422298120,675062520,902114640,1036535760,1538528160,1969520280,2792029680

%N a(n) = (prime(n)^5 - prime(n))/2.

%H Vincenzo Librandi, <a href="/A138424/b138424.txt">Table of n, a(n) for n = 1..200</a>

%F a(n) = A138404(n)/2. - _R. J. Mathar_, Oct 15 2017

%t a = {}; Do[p = Prime[n]; AppendTo[a, (p^5 - p)/2], {n, 1, 50}]; a

%t (#^5-#)/2&/@Prime[Range[30]] (* _Harvey P. Dale_, Oct 01 2017 *)

%o (Magma) [(NthPrime((n))^5 - NthPrime((n)))/2: n in [1..30] ]; // _Vincenzo Librandi_, Jun 18 2011

%o (PARI) forprime(p=2,1e3,print1((p^5-p)/2", ")) \\ _Charles R Greathouse IV_, Jul 15 2011

%K nonn,easy

%O 1,1

%A _Artur Jasinski_, Mar 19 2008