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

1,1

Comments

For definition, see comment of A175522.

Links

Table of n, a(n) for n=1..26.

Formula

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

Mathematica

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

Prog

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

Crossrefs

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

Sequence in context: A131120 A115195 A095384 * A362664 A115899 A183527

Adjacent sequences: A177081 A177082 A177083 * A177085 A177086 A177087

Keyword

nonn,more

Author

Vladimir Shevelev, Dec 09 2010

Extensions

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

Status

approved