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 A143290 Number of binary words of length n containing at least one subword 10^{10}1 and no subwords 10^{i}1 with i<10. 2
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 17, 23, 31, 41, 53, 67, 83, 101, 121, 143, 168, 198, 236, 285, 348, 428, 528, 651, 800, 978, 1188, 1434, 1722, 2061, 2464, 2948, 3534, 4247, 5116, 6174, 7458, 9009, 10873, 13103, 15762, 18927 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,14 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (2,-1,0,0,0,0,0,0,0,0,1,0,-1,0,0,0,0,0,0,0,0,0,-1). FORMULA G.f.: x^12/((x^11+x-1)*(x^12+x-1)). a(n) = A017905(n+21)-A017906(n+23). a(n) = 2*a(n-1) -a(n-2) +a(n-11) -a(n-13) -a(n-23). - Vincenzo Librandi, Jun 05 2013 EXAMPLE a(13)=2 because 2 binary words of length 13 have at least one subword 10^{10}1 and no subwords 10^{i}1 with i<10: 0100000000001, 1000000000010. MAPLE a:= n-> coeff(series(x^12/((x^11+x-1)*(x^12+x-1)), x, n+1), x, n): seq(a(n), n=0..60); MATHEMATICA CoefficientList[Series[x^12 / ((x^11 + x - 1) (x^12 + x - 1)), {x, 0, 60}], x] (* Vincenzo Librandi, Jun 05 2013 *) PROG (MAGMA) [n le 12 select 0 else n le 23 select n-12 else 2*Self(n-1)-Self(n-2) +Self(n-11)-Self(n-13)-Self(n-23): n in [1..60]]; // Vincenzo Librandi, Jun 05 2013 CROSSREFS Cf. A017905, A017906, 10th column of A143291. Sequence in context: A107062 A178538 A017904 * A272038 A044961 A044823 Adjacent sequences:  A143287 A143288 A143289 * A143291 A143292 A143293 KEYWORD nonn,easy AUTHOR Alois P. Heinz, Aug 04 2008 STATUS approved

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