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A069975 n*(16n^2-1). 0

%I

%S 15,126,429,1020,1995,3450,5481,8184,11655,15990,21285,27636,35139,

%T 43890,53985,65520,78591,93294,109725,127980,148155,170346,194649,

%U 221160,249975,281190,314901,351204,390195,431970,476625,524256,574959

%N n*(16n^2-1).

%C Sum(n>0, 1/a(n)) = 3log(2)-2 = A016631 - 2. (Ramanujan)

%C Conjecture: satisfies a linear recurrence having signature (4, -6, 4, -1). - _Harvey P. Dale_, Dec 17 2018

%t Table[n(16n^2-1),{n,40}] (* _Harvey P. Dale_, Dec 17 2018 *)

%o (PARI) a(n) = n*(16*n^2-1); \\ _Michel Marcus_, Nov 25 2013

%K easy,nonn

%O 1,1

%A _Benoit Cloitre_, Apr 30 2002

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Last modified March 30 09:49 EDT 2020. Contains 333125 sequences. (Running on oeis4.)