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A130902 a(n) is the number of binary strings of length n such that there exist 4 or more ones in a subsequence of length 5 or less. 1

%I #11 Jul 19 2020 13:28:53

%S 0,0,0,1,6,16,39,91,207,463,1014,2188,4671,9888,20786,43435,90302,

%T 186934,385547,792642,1625035,3323393,6782041,13813588,28087444,

%U 57023945,115614136,234117510,473564782,956961354,1932059363,3897575310,7856867785,15827584881

%N a(n) is the number of binary strings of length n such that there exist 4 or more ones in a subsequence of length 5 or less.

%H Matthew House, <a href="/A130902/b130902.txt">Table of n, a(n) for n = 0..3304</a>

%H <a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (3,-1,-2,1,0,-4,-1,2,0,-1,2).

%F a(n) = 2^n - A125513(n).

%F G.f.: x^3*(-1-3*x+x^2+x^3-x^4+x^5+x^6) / ( (2*x-1)*(x^10+x^7-2*x^5-x^4-x^2-x+1) ). - _R. J. Mathar_, Nov 28 2011

%t LinearRecurrence[{3,-1,-2,1,0,-4,-1,2,0,-1,2},{0,0,0,1,6,16,39,91,207,463,1014},40] (* _Harvey P. Dale_, Jul 19 2020 *)

%Y Cf. A118647, A118646.

%K nonn

%O 0,5

%A _Tanya Khovanova_, Sep 28 2007

%E More terms from _Matthew House_, Dec 26 2016

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Last modified April 24 20:08 EDT 2024. Contains 371963 sequences. (Running on oeis4.)