A126696 Tenth-squares: floor(n/10)*ceiling(n/10).

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 6, 6, 6, 6, 6, 6, 6, 6, 6, 9, 12, 12, 12, 12, 12, 12, 12, 12, 12, 16, 20, 20, 20, 20, 20, 20, 20, 20, 20, 25, 30, 30, 30, 30, 30, 30, 30, 30, 30, 36, 42, 42, 42, 42, 42, 42, 42, 42, 42, 49, 56, 56, 56, 56, 56, 56, 56, 56, 56

Offset: 0

Author

Jonathan Vos Post, May 27 2007

Keywords

• easy
• nonn

Crossrefs

Cf. A002620, A024206, A072280, A002984, A007590, A000212, A118015, A056827, A118013.

Programs

Magma

[ Floor(n/10)*Ceiling(n/10) : n in [0..100]];

Mathematica

f[n_]:=Module[{c=n/10},Floor[c]Ceiling[c]];f[Range[0,90]] (* Harvey P. Dale, Apr 04 2011 *)

Formula

Equivalently, floor(n^2/100).