login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A119408 Decimal equivalent of the binary string generated by the n X n identity matrix. 3
1, 9, 273, 33825, 17043521, 34630287489, 282578800148737, 9241421688590303745, 1210107565283851686118401, 634134936313486520338360567809, 1329552593586084350528447794605199361, 11151733894906779683522195341810241573494785 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
a(n) is divisible by 2^n - 1. a(n) == n mod 2^(n+1) - 1. - Robert Israel, Jun 09 2015
LINKS
FORMULA
a(n) = 2^((n+1)(n-1)) + 2^((n+1)(n-2)) + ... + 1 where n=2,3,...
a(n) = (2^n*2^(n^2)-1)/(2*2^n-1). - Stuart Bruff, Jun 08 2015
EXAMPLE
n=2: [1 0; 0 1] == 1001_2 = 9;
n=3: [1 0 0; 0 1 0; 0 0 1] == 100010001_2 = 273;
n=4: [1 0 0 0; 0 1 0 0; 0 0 1 0; 0 0 0 1] == 1000010000100001_2 = 33825.
MATHEMATICA
For[n=2, n<=10, Print[n, " ", Sum[2^((n+1)(k-1)), {k, 1, n}]]; n++ ]
Table[FromDigits[Flatten[IdentityMatrix[n]], 2], {n, 15}] (* Harvey P. Dale, Dec 31 2021 *)
PROG
(MATLAB) for n = 1:10 bi2de((reshape(eye(n), length(eye(n))^2, 1))') end
% Kyle Stern, Dec 14 2011
(PARI) a(n)=(2^n*2^(n^2)-1)/(2*2^n-1) \\ Charles R Greathouse IV, Jun 09 2015
CROSSREFS
Cf. A128889.
Sequence in context: A197981 A188812 A197768 * A295898 A330604 A336259
KEYWORD
nonn,base
AUTHOR
Lynn R. Purser, Jul 25 2006
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)