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A176234 Floor(sqrt(n))-perfect numbers. 2
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified October 22 18:45 EDT 2021. Contains 348175 sequences. (Running on oeis4.)