A177084 Ceiling(n/3)-perfect numbers.

2, 3, 4, 10, 14, 50, 52, 130, 184, 315, 688, 988, 2528, 6490, 35456, 396916, 537088, 538112, 801376, 1297312, 8452096, 8456192, 35221184, 53996590, 134520832, 222469702

Offset: 1

Author

Vladimir Shevelev, Dec 09 2010

Keywords

• nonn
• more

Comments

For definition, see comment of A175522.

Crossrefs

Cf. A000396, A002264, A175522, A175807, A175853, A177050.

Programs

Mathematica

aQ[n_] := DivisorSum[n, Ceiling[#/3] &, # < n &] == Ceiling[n/3]; Select[Range[10^6], aQ] (* Amiram Eldar, Jul 20 2019 *)

Sage

is_A177084 = lambda n: sum(ceil(d/3) for d in divisors(n)) == 2*ceil(n/3) # D. S. McNeil, Dec 10 2010

Formula

{n: Sum_{d|n, dA002264(2+d) = A002264(2+n)}. - R. J. Mathar, Dec 11 2010

Extensions

a(21)-a(26) from Amiram Eldar, Jul 20 2019