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!)
A068336 a(1) = 1; a(n+1) = 1 + sum{k|n} a(k), sum is over the positive divisors, k, of n. 5
1, 2, 4, 6, 10, 12, 20, 22, 32, 38, 52, 54, 80, 82, 106, 122, 154, 156, 208, 210, 268, 294, 350, 352, 454, 466, 550, 588, 700, 702, 876, 878, 1032, 1090, 1248, 1280, 1548, 1550, 1762, 1848, 2138, 2140, 2530, 2532, 2888, 3042, 3396, 3398, 3974, 3996, 4502 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Equals row sums of triangle A160182. - Gary W. Adamson, May 03 2009

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

EXAMPLE

a(7) = 1 +a(1) +a(2) +a(3) +a(6) = 1 + 1 +2 +4 +12 = 20.

MATHEMATICA

a[1] = 1; a[n_] := a[n] = 1 + Sum[a[k], {k, Divisors[n-1]}]; Table[ a[n], {n, 1, 51}] (* Jean-Fran├žois Alcover, Dec 20 2011 *)

PROG

(Haskell)

a068336 n = a068336_list !! (n-1)

a068336_list = 1 : f 1 where

   f x = (1 + sum (map a068336 $ a027750_row x)) : f (x + 1)

-- Reinhard Zumkeller, Dec 20 2014

CROSSREFS

Cf. A003238.

Cf. A160182. - Gary W. Adamson, May 03 2009

Cf. A027750.

Sequence in context: A083887 A064374 A000885 * A194944 A133871 A068514

Adjacent sequences:  A068333 A068334 A068335 * A068337 A068338 A068339

KEYWORD

nonn

AUTHOR

Leroy Quet, Feb 27 2002

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 3 12:46 EST 2016. Contains 278734 sequences.