login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A211063 Number of 2 X 2 matrices having all terms in {1,...,n} and determinant >=3n. 2
0, 0, 0, 0, 8, 38, 122, 284, 589, 1080, 1848, 2933, 4515, 6577, 9366, 12888, 17444, 22928, 29864, 37986, 48057, 59656, 73413, 89307, 108002, 129068, 153386, 180636, 212111, 246683, 286126, 329135, 378047, 431242, 490425, 555118 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

For a guide to related sequences, see A210000.

LINKS

Chai Wah Wu, Table of n, a(n) for n = 0..2000

MATHEMATICA

a = 1; b = n; z1 = 35;

t[n_] := t[n] = Flatten[Table[w*z - x*y, {w, a, b}, {x, a, b}, {y, a, b}, {z, a, b}]]

c[n_, k_] := c[n, k] = Count[t[n], k]

s[n_, m_] := s[n, m] = Sum[c[n, k], {k, 1, m}]

Table[s[n, n^2]-s[n, 3n-1], {n, 1, z1}] (* A211063 *)

CROSSREFS

Cf. A210000.

Sequence in context: A319960 A163832 A139798 * A065762 A034009 A038732

Adjacent sequences:  A211060 A211061 A211062 * A211064 A211065 A211066

KEYWORD

nonn

AUTHOR

Clark Kimberling, Mar 31 2012

EXTENSIONS

Offset corrected by Chai Wah Wu, Jan 10 2017

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 14 17:32 EST 2019. Contains 329979 sequences. (Running on oeis4.)