Let σ(m) be the divisor function of m. Then two numbers m and n are a quasiamicable pair if σ(m) = σ(n) = m + n + 1. The first few are (48, 75), (140, 195), (1050, 1925), (1575, 1648), ... (OEIS A005276). Quasiamicable numbers are sometimes called betrothed numbers or reduced amicable pairs.
