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A123339 a(1)=1. For n >= 2, a(n) = Sum_{k=1..(n-1)} k^b(a(n-k),k), where k^b(m,k) is the highest power of k that divides m (and where b(m,k) is a nonnegative integer). 1
1, 1, 2, 3, 5, 5, 8, 7, 15, 13, 17, 13, 12, 17, 30, 17, 20, 19, 26, 23, 29, 25, 34, 37, 57, 25, 59, 45, 28, 43, 81, 43, 55, 113, 34, 41, 82, 41, 39, 135, 40, 43, 124, 71, 108, 49, 76, 73, 69, 77, 121, 81, 100, 61, 151, 55, 136, 107, 65, 59, 212, 181, 181, 67, 74, 83, 103, 67 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

1^b(m,1) is considered here to be 1 for all m.

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..1000

EXAMPLE

The highest power of 1 dividing a(6) is 1. The highest power of 2 dividing a(5) is 1. The highest power of 3 dividing a(4) is 3. The highest power of 4 dividing a(3) is 1. The highest power of 5 dividing a(2) is 1. And the highest power of 6 dividing a(1) is 1. So a(7) = 1+1+3+1+1+1 = 8.

MATHEMATICA

b[m_, k_] := If[k == 1, 1, IntegerExponent[m, k]]; f[l_List] := Append[l, Sum[k^b[l[[Length[l] + 1 - k]], k], {k, Length[l]}]]; Nest[f, {1}, 70] (* Ray Chandler, Oct 17 2006 *)

CROSSREFS

Sequence in context: A304493 A208323 A067284 * A246104 A256654 A204926

Adjacent sequences:  A123336 A123337 A123338 * A123340 A123341 A123342

KEYWORD

nonn

AUTHOR

Leroy Quet, Oct 11 2006

EXTENSIONS

Extended by Ray Chandler, Oct 17 2006

STATUS

approved

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Last modified September 24 09:10 EDT 2021. Contains 347630 sequences. (Running on oeis4.)