A228641 Volume of torus (rounded down) with major radius = n and minor radius = n/3.

2, 17, 59, 140, 274, 473, 752, 1122, 1598, 2193, 2919, 3789, 4818, 6018, 7402, 8983, 10775, 12791, 15043, 17545, 20311, 23353, 26685, 30319, 34269, 38548, 43169, 48146, 53491, 59217, 65338, 71868, 78818, 86203, 94035, 102328, 111094, 120347, 130101, 140367, 151160

Offset

1,1

Links

K. D. Bajpai, Table of n, a(n) for n = 1..100

Wikipedia, Torus

Formula

a(n) = floor( 2/9 * Pi^2 * n^3 ).

Example

a(6) = 473 :  volume = ((2  *Pi * n) * (Pi * (n/3)^2)) = ((2 *Pi * 6) * (Pi * (6/3)^2)) = 473.7410114 and floor(473.7410114) =  473.

Maple

KD := proc() local a; a:=floor( evalf( (2*Pi*n)*(Pi*(n/3)^2) ) ); RETURN (a) :end: seq(KD(), n=1..50);

Prog

(PARI) a(n)=floor(2/9*Pi^2*n^3) \\ Charles R Greathouse IV, Aug 28 2013

Crossrefs

Cf. A228272.

Sequence in context: A368390 A175450 A071402 * A226417 A191295 A002430

Adjacent sequences: A228638 A228639 A228640 * A228642 A228643 A228644

Keyword

nonn

Author

K. D. Bajpai, Aug 28 2013

Status

approved