-2139

Appears in sequences

• arcsin(arctan(tanh(x)))=x-3/3!*x^3+49/5!*x^5-2139/7!*x^7+181921/9!*x^9...at n=3A012223
• Sequence of coefficients arising in study of generating function for A067619.at n=43A186545
• First differences of number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 361", based on the 5-celled von Neumann neighborhood.at n=27A271417