A065506 - OEIS

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A065506

Number of (binary) bit strings of length n having an even length block of 0's followed by an odd length block of 1's.

1, 2, 7, 15, 39, 84, 196, 419, 928, 1965, 4227, 8871, 18742, 39032, 81481, 168606, 349011, 718371, 1477783, 3028412, 6200296, 12660171, 25823604, 52569417, 106908199, 217086287, 440402878, 892384788, 1806730377, 3654428154 (list; graph; refs; listen; history; internal format)

	OFFSET	`3,2`
	LINKS	`Index to sequences with linear recurrences with constant coefficients, signature (2,3,-5,-2).`
	FORMULA	`O.g.f.: x^3/[(1-2x)(1-3x^2-x^3)`
	CROSSREFS	`A065455(n) = 2^n - a(n)` `Sequence in context: A131412 A151998 A052130 * A121165 A093652 A200862` `Adjacent sequences: A065503 A065504 A065505 * A065507 A065508 A065509`
	KEYWORD	`nonn`
	AUTHOR	`Len Smiley (smiley(AT)math.uaa.alaska.edu), Nov 26 2001`

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Last modified February 15 09:15 EST 2012. Contains 205753 sequences.