login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A210290 Number of 2 X 2 matrices with all elements in {0,1,...,n} and nonnegative determinant. 2
1, 13, 56, 160, 369, 733, 1328, 2216, 3505, 5285, 7680, 10792, 14809, 19813, 26024, 33600, 42721, 53549, 66384, 81336, 98761, 118821, 141784, 167888, 197561, 230917, 268352, 310176, 356753, 408285, 465376, 528088, 597049, 672533, 754944, 844744, 942425 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

See A210000 for a guide to related sequences.

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..1000

FORMULA

a(n) = ((n+1)^4 + A059306(n))/2. - Andrew Howroyd, Apr 28 2020

MATHEMATICA

a = 0; b = n; z1 = 45;

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]

c1[n_, m_] := c1[n, m] = Sum[c[n, k], {k, 0, m}]

Table[c1[n, n^2], {n, 0, z1}]   (* A210290 *)

CROSSREFS

Cf. A059306, A210000.

Sequence in context: A061161 A212053 A264853 * A007202 A222161 A218593

Adjacent sequences:  A210287 A210288 A210289 * A210291 A210292 A210293

KEYWORD

nonn

AUTHOR

Clark Kimberling, Mar 19 2012

EXTENSIONS

Terms a(34) and beyond from Andrew Howroyd, Apr 28 2020

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 October 16 17:39 EDT 2021. Contains 348042 sequences. (Running on oeis4.)