A177052 - OEIS

%I #20 Nov 17 2019 01:44:49

%S 6,12,18,20,24,28,30,36,40,42,48,54,56,60,66,70,72,78,80,84,88,90,96,

%T 100,102,104,108,112,114,120,126,132,138,140,144,150,156,160,162,168,

%U 174,176,180,186,192,196,198,200,204,208,210,216,220,222,224,228

%N Ceiling(n/2)-abundant numbers.

%C For definition, see A175522.

%C All positive numbers == 0 (mod 6) are in the sequence (basically A008588). In addition, note that all odd primes are ceiling(n/2)-deficient numbers. The first odd term of the sequence is 315.

%H Amiram Eldar, <a href="/A177052/b177052.txt">Table of n, a(n) for n = 1..10000</a>

%F {n : Sum_{d|n, d<n} A004526(1+d) > A004526(1+n)}. [_R. J. Mathar_, Dec 11 2010]

%o (Sage) is_A177052 = lambda n: sum(ceil(d/2) for d in divisors(n)) > 2*ceil(n/2) # _D. S. McNeil_, Dec 10 2010

%o (PARI) isok(n) = sumdiv(n, d, (d<n)*ceil(d/2)) > ceil(n/2); \\ _Michel Marcus_, Feb 08 2016

%Y Cf. A177050 (perfect version), A005100, A005101, A175524, A175526, A175811, A175821, A175853.

%K nonn

%O 1,1

%A _Vladimir Shevelev_, Dec 09 2010