This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A055389 a(0)=1, then twice the Fibonacci sequence. 14
 1, 2, 2, 4, 6, 10, 16, 26, 42, 68, 110, 178, 288, 466, 754, 1220, 1974, 3194, 5168, 8362, 13530, 21892, 35422, 57314, 92736, 150050, 242786, 392836, 635622, 1028458, 1664080, 2692538, 4356618, 7049156, 11405774, 18454930, 29860704, 48315634, 78176338 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS a(n) is the number of sequences over the alphabet {0,1} such that all maximal blocks (of both 0's and 1's) have odd length. - Geoffrey Critzer, Mar 06 2012 LINKS Michael De Vlieger, Table of n, a(n) for n = 0..4785 Yuhong Guo, Some Identities for Palindromic Compositions Without 2's, Journal of Mathematical Research with Applications 38.2 (2018): 130-136. Index entries for linear recurrences with constant coefficients, signature (1,1). FORMULA G.f.: (1+x-x^2)/(1-x-x^2). EXAMPLE a(4) = 6 because we have 0001, 0101, 0111, 1000, 1010, 1110. - Geoffrey Critzer, Mar 06 2012 MATHEMATICA Join[{1}, Table[2*Fibonacci[n], {n, 70}]] (* Vladimir Joseph Stephan Orlovsky, Feb 10 2012 *) CoefficientList[Series[(1 + x - x^2)/(1 - x - x^2), {x, 0, 38}], x] (* Michael De Vlieger, Jun 14 2018 *) PROG (PARI) a(n)=if(n, 2*fibonacci(n), 1) \\ Charles R Greathouse IV, Oct 03 2016 CROSSREFS Essentially the same as A006355. Sequence in context: A006355 * A163733 A198834 A270925 A084202 A300865 Adjacent sequences:  A055386 A055387 A055388 * A055390 A055391 A055392 KEYWORD easy,nonn AUTHOR Robert G. Wilson v, Jul 05 2000 EXTENSIONS More terms from James A. Sellers, Jul 07 2000 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 17 15:28 EDT 2018. Contains 313816 sequences. (Running on oeis4.)