18454930

Appears in sequences

• Number of binary vectors of length n containing no singletons.at n=36A006355
• Number of distinct permutations generated by shuffling n cards with "clump size" <= 2.at n=32A047992
• Expansion of 2*x*(1 - x)/(1 - 3*x + x^2).at n=18A052995
• Layer counting sequence for hyperbolic tessellation by cuspidal triangles of angles (Pi/3,Pi/3,0) (this is the classical modular tessellation).at n=33A054886
• a(0) = 1, then twice the Fibonacci sequence.at n=35A055389
• Row sums of array T in A055818; twice the odd-indexed Fibonacci numbers after initial term.at n=18A055819
• Number of ways to tile a 3 X 2n room with 1 X 2 Tatami mats. At most 3 Tatami mats may meet at a point.at n=33A068922
• Numbers with two representations as the sum of two Fibonacci numbers.at n=32A078642
• Number of meaningful differential operations of the n-th order on the space R^6.at n=31A090991
• a(n) = 2*F(n-1) = L(n) - F(n), where F(n) and L(n) are Fibonacci and Lucas numbers respectively.at n=36A118658
• Number of base 4 n-digit numbers with adjacent digits differing by one or less.at n=17A126358
• Expansion of g.f. x*(1+x+x^2)/(1-x-x^2).at n=34A128588
• Row sums of triangle A131779.at n=33A131780
• Expansion of x - x^2*(2*x+1)*(x^2-2) / ( (x^2-x-1)*(x^2+x-1) ).at n=34A133585
• Inverse score permutation of an Fibonacci -anti-Fibonacci zero sum game of 2 X 2 matrices.at n=22A134016
• First differences of A137976 after having added two leading ones.at n=14A138298
• Number of n X 2 binary arrays with all 1s connected, a path of 1s from top row to bottom row, and no 1 having more than two 1s adjacent.at n=32A163714
• Number of n X 2 binary arrays with all 1's connected, all corners 1, and no 1 having more than two 1's adjacent.at n=36A163733
• a(n) = 2*(A000045(n)-(n mod 2)) + 1 + (n mod 2).at n=35A166012
• a(n) = (F(2*n-1) + F(2*n+2)) * (5/6 - cos(2*Pi*n/3)/3), where F(n) = Fibonacci(n).at n=17A179134