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A154806
Numbers such that every run length in base 2 is 4.
2
15, 240, 3855, 61680, 986895, 15790320, 252645135, 4042322160, 64677154575, 1034834473200, 16557351571215, 264917625139440, 4238682002231055, 67818912035696880, 1085102592571150095, 17361641481138401520
OFFSET
1,1
COMMENTS
a(n) is the number whose binary representation is A154805(n).
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
MATHEMATICA
LinearRecurrence[{16, 1, -16}, {15, 240, 3855}, 20] (* Harvey P. Dale, Apr 13 2018 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Omar E. Pol, Jan 25 2009
EXTENSIONS
More terms from Sean A. Irvine, Feb 21 2010
STATUS
approved