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A068336 a(1) = 1; a(n+1) = 1 + sum{k|n} a(k), sum is over the positive divisors, k, of n. 4
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,changed

AUTHOR

Leroy Quet, Feb 27 2002

STATUS

approved

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Last modified December 20 08:42 EST 2014. Contains 252241 sequences.