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Johnson solid J_7.

The Elsasser function is defined by the integral E(y,u)=int_(-1/2)^(1/2)exp[-(2piyusinh(2piy))/(cosh(2piy)-cos(2pix))]dx. (1) Special values include E(0,u) = 1 (2) E(y,0) = ...

A knot K is an n-embeddable knot if it can be placed on a genus n standard embedded surface without crossings, but K cannot be placed on any standardly embedded surface of ...

A surface S is n-embeddable if it can be placed in R^n-space without self-intersections, but cannot be similarly placed in any R^k for k<n. A surface so embedded is said to ...

An embedding is a representation of a topological object, manifold, graph, field, etc. in a certain space in such a way that its connectivity or algebraic properties are ...

The ordinary differential equation (x^py^')^'+/-x^sigmay^n=0.

The second-order ordinary differential equation (x^2y^')^'+x^2y^n=0.

An emirp ("prime" spelled backwards) is a prime whose (base 10) reversal is also prime, but which is not a palindromic prime. The first few are 13, 17, 31, 37, 71, 73, 79, ...

Define an emirpimes ("semiprime" spelled backwards) as a semiprime whose (base 10) reversal is a different semiprime. The first such number is 15, because 15 reversed is 51 ...

The empire problem, also known as the m-pire problem) asks for the maximum number of colors needed to color countries such that no two countries sharing a common border have ...