51680

Appears in sequences

• a(1) = 1, a(2) = 0; for n > 2, a(n) = n*Fibonacci(n-2) (with the convention Fibonacci(0)=0, Fibonacci(1)=1).at n=19A006490
• Expansion of Product_{k>=1} (1 - x^k)^20.at n=11A010826
• Fibonacci sequence beginning 0, 20.at n=18A022354
• a(n) = (Lucas(2*n) - Lucas(n))/2.at n=12A049681
• Number of hands that peg n points in the "show" phase of 6-card cribbage.at n=11A066354
• Numbers k such that phi(k) = bigomega(k)*tau(k)^2.at n=41A068540
• Number of cycles of length 4 in the queen graph associated with an n X n chessboard.at n=9A156001
• Number of (n+1)X(n+1) 0..3 arrays with the sums of 2X2 subblocks nondecreasing rightwards and downwards.at n=1A204302
• Number of (n+1)X3 0..3 arrays with the sums of 2X2 subblocks nondecreasing rightwards and downwards.at n=1A204304
• T(n,k)=Number of (n+1)X(k+1) 0..3 arrays with the sums of 2X2 subblocks nondecreasing rightwards and downwards.at n=4A204309