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A110794 a(1)=1, a(n) = Sum_{k=1..n-1} (number of divisors of a(k) that also divide n). 0
1, 1, 2, 4, 4, 8, 6, 16, 9, 15, 10, 26, 13, 21, 21, 30, 16, 36, 18, 42, 35, 34, 22, 62, 28, 45, 40, 61, 28, 76, 31, 67, 43, 55, 48, 93, 36, 61, 53, 90, 40, 100, 43, 85, 81, 70, 46, 125, 55, 100, 67, 97, 53, 116, 74, 120, 73, 90, 58, 183, 63, 98, 104, 127, 84, 136, 68, 135, 90 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..69.

EXAMPLE

The divisors of the first 5 terms of the sequence are a(1):1; a(2):1; a(3):1,2; a(4):1,2,4; a(5):1,2,4. Eight of these divisors divide 6. (These divisors are 1;1;1,2;1,2;1,2.) So a(6) = 8.

MATHEMATICA

a = {1}; Do[AppendTo[a, Sum[Length[Select[Divisors[a[[i]]], Mod[Length[a] + 1, # ] == 0 &]], {i, 1, Length[a]}]], {70}]; a (* Stefan Steinerberger, Oct 16 2007 *)

CROSSREFS

Sequence in context: A184396 A329718 A077764 * A117295 A235999 A093820

Adjacent sequences:  A110791 A110792 A110793 * A110795 A110796 A110797

KEYWORD

nonn

AUTHOR

Leroy Quet, Apr 26 2007

EXTENSIONS

More terms from Stefan Steinerberger, Oct 16 2007

STATUS

approved

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Last modified October 26 04:54 EDT 2021. Contains 348256 sequences. (Running on oeis4.)