login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons 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!)
A145641 Numbers whose binary representation is the concatenation of n 1's, n 0's and n 1's. 4
5, 51, 455, 3855, 31775, 258111, 2080895, 16711935, 133956095, 1072694271, 8585742335, 68702703615, 549688713215, 4397778092031, 35183298379775, 281470681808895, 2251782633947135, 18014329790267391, 144114913198473215, 1152920405096267775, 9223367638810361855 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers whose binary representation are the members of A138721.

LINKS

Table of n, a(n) for n=1..21.

Index entries for linear recurrences with constant coefficients, signature (15,-70,120,-64).

FORMULA

G.f.: x*(40*x^2-24*x+5)/((x-1)*(2*x-1)*(4*x-1)*(8*x-1)). - Colin Barker, Nov 04 2012

a(n) = (2^n-1)*(2^(2*n)+1) = 8^n - 4^n + 2^n - 1. - Alois P. Heinz, Nov 04 2012

MAPLE

a:= n-> 8^n-4^n+2^n-1:

seq(a(n), n=1..30); # Alois P. Heinz, Nov 04 2012

CROSSREFS

Cf. A138721.

Sequence in context: A068540 A208997 A041043 * A317782 A195211 A106415

Adjacent sequences:  A145638 A145639 A145640 * A145642 A145643 A145644

KEYWORD

easy,nonn,base

AUTHOR

Omar E. Pol, Oct 14 2008

EXTENSIONS

More terms from Colin Barker, Nov 04 2012

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 20 11:06 EST 2020. Contains 331083 sequences. (Running on oeis4.)