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

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

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 | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 10 21:23 EST 2016. Contains 279011 sequences.