549990

Appears in sequences

• Dimension of 4-variable non-commutative harmonics (twisted derivative). The dimension of the space of non-commutative polynomials in 4 variables which are killed by all symmetric differential operators (where for a monomial w, d_{xi} ( xi w ) = w and d_{xi} ( xj w ) = 0 for i/=j).at n=10A122368
• Nonunitary near-perfect numbers: k such that nusigma(k) = k + d where d is a nonunitary divisor of k.at n=40A362969