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%I #9 Dec 25 2016 15:43:40
%S 1,2,27,100,245,486,847,1352,2025,2890,3971,5292,6877,8750,10935,
%T 13456,16337,19602,23275,27380,31941,36982,42527,48600,55225,62426,
%U 70227,78652,87725,97470,107911,119072,130977,143650,157115,171396,186517,202502,219375
%N a(n) = 4 * n^3 - 3 * n + 1.
%H Daniel Suteu, <a href="/A280089/b280089.txt">Table of n, a(n) for n = 0..750</a>
%F a(n) = (2n - 1)^2 * (n + 1).
%F Prod_{k >= 1}(A033430(k) / a(k)) = Pi.
%t Table[4n^3 - 3n + 1, {n, 0, 39}] (* _Alonso del Arte_, Dec 25 2016 *)
%o (PARI) a(n) = (2*n-1)^2 * (n+1).
%Y Cf. A033430.
%K nonn,easy
%O 0,2
%A _Daniel Suteu_, Dec 25 2016
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