where
is the divisor function. Deficient numbers are
sometimes called defective numbers (Singh 1997). Primes,
prime powers, all proper
divisors of a perfect number, and all divisors
of a deficient number are deficient. The first few deficient numbers are 1, 2, 3,
4, 5, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 21, 22, 23, ... (OEIS A005100).
for which
is the divisor function. Deficient numbers are
sometimes called defective numbers (Singh 1997). Primes,
prime powers, all proper
divisors of a perfect number, and all divisors
of a deficient number are deficient. The first few deficient numbers are 1, 2, 3,
4, 5, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 21, 22, 23, ... (OEIS A005100).
