A171975 Integer part of the circumsphere radius of a regular tetrahedron with edge length n.

0, 1, 1, 2, 3, 3, 4, 4, 5, 6, 6, 7, 7, 8, 9, 9, 10, 11, 11, 12, 12, 13, 14, 14, 15, 15, 16, 17, 17, 18, 18, 19, 20, 20, 21, 22, 22, 23, 23, 24, 25, 25, 26, 26, 27, 28, 28, 29, 30, 30, 31, 31, 32, 33, 33, 34, 34, 35, 36, 36, 37, 37, 38, 39, 39, 40, 41, 41, 42, 42, 43, 44, 44, 45, 45

Offset

1,4

Comments

-3 <= 4*a(n) - 3*A171974(n) < 3;

a(n)*A171974(n) <= A007590(n).

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Eric Weisstein's World of Mathematics, Tetrahedron

Wikipedia, Tetrahedron

Formula

a(n) = floor(n*sqrt(6)/4).

Prog

(Haskell)
a171975 = floor . (/ 4) . (* sqrt 6) . fromInteger
-- Reinhard Zumkeller, Dec 15 2012

Crossrefs

Cf. A171973, A171972, A022840. Beatty sequence of A187110.

Sequence in context: A244229 A317596 A057355 * A160511 A079952 A055930

Adjacent sequences: A171972 A171973 A171974 * A171976 A171977 A171978

Keyword

nonn

Author

Reinhard Zumkeller, Jan 20 2010

Status

approved