A057057 Let R(i,j) be the rectangle with antidiagonals 1; 2,3; 4,5,6; ...; C(n,3) is in antidiagonal a(n).

1, 3, 4, 6, 8, 11, 13, 15, 18, 21, 24, 27, 30, 33, 37, 40, 44, 48, 52, 55, 60, 64, 68, 72, 76, 81, 85, 90, 95, 100, 104, 109, 114, 119, 125, 130, 135, 141, 146, 152, 157, 163, 168, 174, 180, 186, 192, 198, 204, 210, 216, 223, 229

Offset

3,2

Links

Table of n, a(n) for n=3..55.

Formula

Round(sqrt(2*binomial(n, 3))). - Vladeta Jovovic, Jun 14 2003

Mathematica

Table[Round[Sqrt[2*Binomial[n, 3]]], {n, 3, 60}] (* Harvey P. Dale, Nov 16 2021 *)

Crossrefs

Cf. A057045, A057062, A057048, A022846, A057054.

Sequence in context: A020901 A181714 A371594 * A186154 A030711 A030761

Adjacent sequences: A057054 A057055 A057056 * A057058 A057059 A057060

Keyword

nonn

Author

Clark Kimberling, Jul 30 2000.

Status

approved