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

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A060870 Number of n X n matrices over GF(5) with rank 1. 2
4, 144, 3844, 97344, 2439844, 61027344, 1525839844, 38146777344, 953673339844, 23841853027344, 596046423339844, 14901161071777344, 372529029235839844, 9313225743103027344, 232830643638610839844, 5820766091270446777344 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..200

Index entries for linear recurrences with constant coefficients, signature (31,-155,125).

FORMULA

a(n) = 1/4 * (5^n - 1)^2.

G.f.: -4*x*(5*x+1) / ((x-1)*(5*x-1)*(25*x-1)). [Colin Barker, Dec 23 2012]

EXAMPLE

a(2) = 144 because there are 145 (the second element in sequence A060720) singular 2 X 2 matrices over GF(5), that have rank <= 1 of which only the zero matrix has rank zero so a(2) = 145 - 1 = 144.

MATHEMATICA

Table[(5^n-1)^2/4, {n, 20}] (* or *) LinearRecurrence[{31, -155, 125}, {4, 144, 3844}, 20] (* Harvey P. Dale, Dec 06 2014 *)

PROG

(PARI) { for (n=1, 200, write("b060870.txt", n, " ", (5^n - 1)^2 / 4); ) } \\ Harry J. Smith, Jul 13 2009

CROSSREFS

Cf. A060720.

Sequence in context: A036511 A263386 A186720 * A268894 A084703 A186418

Adjacent sequences:  A060867 A060868 A060869 * A060871 A060872 A060873

KEYWORD

nonn,easy

AUTHOR

Ahmed Fares (ahmedfares(AT)my-deja.com), May 04 2001

EXTENSIONS

More terms from Larry Reeves (larryr(AT)acm.org), May 07 2001

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 January 16 15:53 EST 2019. Contains 319195 sequences. (Running on oeis4.)