21782

Appears in sequences

• a(0) = 1, a(n) = 20*n^2 + 2 for n>0.at n=33A010010
• Numbers n such that sigma(sigma(phi(n))) = sigma(sigma(n)).at n=26A172466
• Number of simple connected graphs on n nodes whose independence number a(g)=5.at n=8A243784
• Arises in a coin-weighing problem.at n=15A293948
• Triangle read by rows: T(n,k) is the number of simple connected graphs on n vertices having independence number k.at n=40A294490
• Number of 123-avoiding stabilized-interval-free permutations of size n.at n=11A363431
• Expansion of (1 + x^2 - x^3)/((1 + x^2 - x^3)^2 - 4*x^2).at n=19A376726
• Square array read by antidiagonals, where the n-th row is the coordination sequence of a certain tiling with an n-dimensional analog of the X pentomino (or Greek cross), n >= 1.at n=61A383338
• Expansion of 1 / ((1-x)^4 - x^6).at n=16A392542