66197

Appears in sequences

• a(n) = Sum_{k=0..n} binomial(2*k,k).at n=9A006134
• Strong pseudoprimes to base 8.at n=32A020234
• Strong pseudoprimes to base 30.at n=26A020256
• Strong pseudoprimes to base 68.at n=37A020294
• Strong pseudoprimes to base 77.at n=18A020303
• Fibonacci sequence beginning 1, 25.at n=18A022395
• Discriminants of real quadratic fields with class number 2 and related continued fraction period length of 15.at n=33A051980
• Number of rational knots of n crossings with signature 0 (chiral pairs counted twice).at n=19A078478
• The O(1) loop model on the square lattice is defined as follows: At every vertex the loop turns to the left or to the right with equal probability, unless the vertex has been visited before, in which case the loop leaves the vertex via the unused edge. Every vertex is visited twice. The probability that a face of the lattice on an n X infinity cylinder is surrounded by four loops is conjectured to be given by a(n)/A_{HT}(n)^2, where A_{HT}(n) is the number of n X n half turn symmetric alternating sign matrices.at n=2A092376
• Expansion of x/((1-x)*sqrt(1-4*x^2)).at n=19A100066
• Expansion of x/((1-x)*sqrt(1-4*x^2)).at n=20A100066
• Binomial transform of number triangle A105632.at n=56A105848
• Antidiagonal sums of A096465.at n=19A124642
• a(n) = a(n-1) + 5*a(n-2) for n >= 2, a(0)=1, a(1)=2.at n=11A133407
• a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4) - a(n-5) with a(0)=0, a(1)=1, a(2)=2, a(3)=3 and a(4)=4.at n=19A135432
• Expansion of (1+2x-sqrt(1-4x^2))/(2(1-x^2)*sqrt(1-4x^2)).at n=19A174783
• Riordan matrix (1/((1-x)*sqrt(1-4*x)),x/(1-x)).at n=45A187887
• Riordan matrix (1/sqrt(1-4*x),x/(1-x)).at n=56A187888
• Numerators of coefficients associated with the second virial coefficient for rigid spheres with imbedded point dipoles.at n=8A336061