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A279888 a(n) = Sum_{k=1..n-1} sigma_3(k)*sigma_5(n-k). 3
0, 1, 42, 569, 4250, 22006, 88004, 293369, 845358, 2186376, 5145646, 11282966, 23143198, 45179324, 83905292, 150271993, 258816840, 433786483, 704268402, 1119633944, 1733618768, 2640037170, 3931060364, 5777392406, 8325691750, 11873200964, 16643954724, 23133008124 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
REFERENCES
J.-P. Serre, A Course in Arithmetic, Springer-Verlag, 1973, Chap. VII, Section 4.
LINKS
FORMULA
a(n) = (11*sigma_9(n)-21*sigma_5(n)+10*sigma_3(n))/5040.
MATHEMATICA
Table[Sum[If[k == 0, 0, DivisorSigma[3, k]] DivisorSigma[5, n - k], {k, 0, n - 1}], {n, 28}] (* Michael De Vlieger, Dec 22 2016 *)
CROSSREFS
Sequence in context: A248449 A245874 A293096 * A104901 A091962 A269659
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Dec 22 2016
STATUS
approved

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Last modified March 1 18:30 EST 2024. Contains 370443 sequences. (Running on oeis4.)