A160183
Triangle, read by rows, obtained by dropping right diagonal from A160182.
Original entry on oeis.org
1, 2, 1, 3, 1, 1, 5, 2, 1, 1, 6, 2, 1, 1, 1, 10, 4, 2, 1, 1, 1, 11, 4, 2, 1, 1, 1, 1, 16, 6, 3, 2, 1, 1, 1, 1, 19, 7, 4, 2, 1, 1, 1, 1, 1, 26, 10, 5, 3, 2, 1, 1, 1, 1, 1
Offset: 1
First few rows of the triangle =
1;
2, 1;
3, 1, 1;
5, 2, 1, 1;
6, 2, 1, 1, 1;
10, 4, 2, 1, 1, 1;
11, 4, 2, 1, 1, 1, 1;
16, 6, 3, 2, 1, 1, 1, 1;
19, 7, 4, 2, 1, 1, 1, 1, 1;
26, 10, 5, 3, 2, 1, 1, 1, 1, 1;
...
A068336
a(1) = 1; a(n+1) = 1 + sum{k|n} a(k), sum is over the positive divisors, k, of n.
Original entry on oeis.org
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
Offset: 1
a(7) = 1 + a(1) + a(2) + a(3) + a(6) = 1 + 1 + 2 + 4 + 12 = 20.
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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
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a[1] = 1; a[n_] := a[n] = 1 + Sum[a[k], {k, Divisors[n-1]}]; Table[ a[n], {n, 1, 51}] (* Jean-François Alcover, Dec 20 2011 *)
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a(n) = if (n==1, 1, 1+ sumdiv(n-1, d, a(d))); \\ Michel Marcus, Oct 30 2017
Showing 1-2 of 2 results.
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