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A069289 Sum of odd divisors of n <= sqrt(n). 11
1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 4, 1, 1, 4, 1, 1, 4, 1, 1, 4, 1, 1, 4, 6, 1, 4, 1, 1, 9, 1, 1, 4, 1, 6, 4, 1, 1, 4, 6, 1, 4, 1, 1, 9, 1, 1, 4, 8, 6, 4, 1, 1, 4, 6, 8, 4, 1, 1, 9, 1, 1, 11, 1, 6, 4, 1, 1, 4, 13, 1, 4, 1, 1, 9, 1, 8, 4, 1, 6, 13, 1, 1, 11, 6, 1, 4, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,9
COMMENTS
a(n) = Sum{d : d = A182469(n,k), d <= A000196(n), k=1..A001227(n)}. - Reinhard Zumkeller, Apr 05 2015
LINKS
FORMULA
G.f.: Sum_{k>=1} (2*k - 1) * x^((2*k - 1)^2) / (1 - x^(2*k - 1)). - Ilya Gutkovskiy, Apr 04 2020
MATHEMATICA
Table[Total[Select[Divisors[n], OddQ[#]&&#<=Sqrt[n]&]], {n, 120}] (* Harvey P. Dale, Jul 16 2017 *)
PROG
(PARI) a(n) = my(ir = sqrtint(n)); sumdiv(n, d, (d % 2) * (d <= ir) * d); \\ Michel Marcus, Jan 14 2014
(Haskell)
a069289 n = sum $ takeWhile (<= a000196 n) $ a182469_row n
-- Reinhard Zumkeller, Apr 05 2015
CROSSREFS
Sequence in context: A362856 A146325 A333807 * A341309 A346778 A097322
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Mar 14 2002
STATUS
approved

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Last modified March 19 04:58 EDT 2024. Contains 370952 sequences. (Running on oeis4.)