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a(n) = floor((2*n^2)/e).
0

%I #22 Nov 11 2024 21:19:56

%S 0,2,6,11,18,26,36,47,59,73,89,105,124,144,165,188,212,238,265,294,

%T 324,356,389,423,459,497,536,576,618,662,707,753,801,850,901,953,1007,

%U 1062,1119,1177,1236,1297,1360,1424,1489,1556,1625,1695,1766,1839

%N a(n) = floor((2*n^2)/e).

%F a(n) = floor((2*n^2)/e).

%t Table[Floor[(2 n^2)/ E ], {n, 1, 60}] (* _Vincenzo Librandi_, Oct 23 2014 *)

%o (Java) int a(int n) {return (int) ((2*Math.pow(x, 2))/Math.exp(1.0)); }

%o (PARI) a(n) = (2*n^2)\exp(1) \\ _Michel Marcus_, Oct 25 2014

%Y Cf. A032635 (floor(n^2/e)).

%K nonn,easy,changed

%O 1,2

%A _Juliann Barbella_, Oct 06 2014

%E More terms from _Vincenzo Librandi_, Oct 23 2014