A176234 Floor(sqrt(n))-perfect numbers.

2, 3, 4, 21, 26, 27, 33, 35, 38, 46, 58, 62, 74, 475, 605, 1083, 1719, 2007, 2151, 2169, 2259, 2313, 2421, 2431, 2439, 2493, 2529, 2547, 2637, 2737, 2763, 2799, 2979, 3123, 3303, 3357, 3367, 3451, 3619, 3681, 3698, 4255, 4465, 4625, 5035, 5125, 5185, 5695, 6205

Offset

1,1

Comments

See definition in comment to A175522.

The even terms begin: 2, 4, 26, 38, 46, 58, 62, 74, 3698, 34226, 34726, ... - Michel Marcus, Feb 08 2016

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

floor(sqrt(35))=5; floor(sqrt(1))+floor(sqrt(5))+floor(sqrt(7))=5. Therefore, 35 is in the sequence.

Mathematica

f[n_] := Sum[Floor[Sqrt[Divisors[n][[i]]]], {i, 1, Length[Divisors[n]] - 1}]; Select[Range[3000], f[#] == Floor[Sqrt[#]] &]

Prog

(PARI) isok(n) = sumdiv(n, d, (d<n)* sqrtint(d)) == sqrtint(n); \\ Michel Marcus, Feb 08 2016

Crossrefs

Cf. A175522, A000396, A175807.

Sequence in context: A303973 A225466 A225472 * A308891 A058780 A183458

Adjacent sequences: A176231 A176232 A176233 * A176235 A176236 A176237

Keyword

nonn

Author

Vladimir Shevelev, Dec 07 2010

Extensions

More terms from Michel Marcus, Feb 08 2016

Status

approved