A152758 Numbers k such that the deficiency of k plus the number of proper divisors of k is not a prime number (see A152864).

1, 8, 12, 15, 24, 25, 30, 32, 33, 35, 36, 39, 40, 42, 44, 48, 50, 51, 54, 56, 60, 63, 65, 66, 68, 69, 72, 78, 80, 81, 84, 85, 87, 90, 92, 96, 98, 100, 102, 105, 108, 112, 114, 116, 117, 120, 121, 123, 126, 128, 129, 130, 132, 136, 138, 140, 141, 143, 144, 148, 150, 153

Offset: 1

Author

Omar E. Pol, Dec 14 2008

Keywords

• easy
• nonn

Crossrefs

Cf. A000005, A000040, A000203, A032741, A033879, A152757, A152770, A152864.

Programs

Maple

with(numtheory): a := proc (n) if isprime(2*n-sigma(n)+tau(n)-1) = false then n else end if end proc: seq(a(n), n = 1 .. 200); # Emeric Deutsch, Jan 08 2009

Extensions

Extended by Emeric Deutsch, Jan 08 2009

Name edited by Jon E. Schoenfield, Jan 06 2019