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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
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
1,2
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
KEYWORD
easy,nonn
AUTHOR
Omar E. Pol, Dec 14 2008
EXTENSIONS
Extended by Emeric Deutsch, Jan 08 2009
Name edited by Jon E. Schoenfield, Jan 06 2019
STATUS
approved