A145641 Numbers whose binary representation is the concatenation of n 1's, n 0's and n 1's.

5, 51, 455, 3855, 31775, 258111, 2080895, 16711935, 133956095, 1072694271, 8585742335, 68702703615, 549688713215, 4397778092031, 35183298379775, 281470681808895, 2251782633947135, 18014329790267391, 144114913198473215, 1152920405096267775, 9223367638810361855

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: A041043 A362516 A369295 * A317782 A342407 A195211

Adjacent sequences: A145638 A145639 A145640 * A145642 A145643 A145644

Keyword

easy,nonn,base,changed

Author

Omar E. Pol, Oct 14 2008

Extensions

More terms from Colin Barker, Nov 04 2012

Status

approved