login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A079580 a(n)= Sum_{d divides n} a(abs(n/d-d)). 0
1, 1, 2, 4, 9, 18, 38, 76, 156, 313, 634, 1268, 2556, 5112, 10260, 20524, 41125, 82250, 164660, 329320, 658954, 1317926, 2636478, 5272956, 10547220, 21094441, 42191418, 84382912, 168770944, 337541888, 675094154, 1350188308, 2700397154 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

a(n) ~ C*2^n with C = .628740040499836347322149351427942214993040272834319137309763934148261658865450483387401211931448206862363011518639795861651335671171128757390830637095743647323023978906898507225697249070040926830707343373261272274541864052203777...

LINKS

Table of n, a(n) for n=0..32.

MATHEMATICA

a[0] = 1; a[n_] := a[n] = Block[{d = Divisors[n], l = DivisorSigma[0, n], k = 1, s = 0}, While[k < l + 1, s = s + a[ Abs[ n/d[[k]] - d[[k]] ]]; k++ ]; s]; Table[a[n], {n, 0, 32}]

CROSSREFS

Sequence in context: A052932 A018097 A215253 * A018000 A036610 A219755

Adjacent sequences:  A079577 A079578 A079579 * A079581 A079582 A079583

KEYWORD

easy,nonn

AUTHOR

Vladeta Jovovic, Jan 25 2003

EXTENSIONS

More terms from Benoit Cloitre and Robert G. Wilson v, Jan 27 2003

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified October 25 08:04 EDT 2014. Contains 248518 sequences.