A154806 Numbers such that every run length in base 2 is 4.

15, 240, 3855, 61680, 986895, 15790320, 252645135, 4042322160, 64677154575, 1034834473200, 16557351571215, 264917625139440, 4238682002231055, 67818912035696880, 1085102592571150095, 17361641481138401520

Offset: 1

Author

Omar E. Pol, Jan 25 2009

Keywords

• easy
• nonn

Comments

a(n) is the number whose binary representation is A154805(n).

Links

• Index entries for linear recurrences with constant coefficients, signature (16,1,-16).

Crossrefs

Cf. A043291, A097262, A152776, A154805, A154808.

Programs

Mathematica

LinearRecurrence[{16,1,-16},{15,240,3855},20] (* Harvey P. Dale, Apr 13 2018 *)

Formula

Conjecture: a(n) = 1/17*2^(4*n+4) + 15/34*(-1)^(n+1) - 1/2. - Vaclav Kotesovec, Nov 30 2012

Empirical g.f.: 15*x / ((x-1)*(x+1)*(16*x-1)). - Colin Barker, Sep 16 2013

Extensions

More terms from Sean A. Irvine, Feb 21 2010