A279888 - OEIS

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A279888

a(n) = Sum_{k=1..n-1} sigma_3(k)*sigma_5(n-k).

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

Seiichi Manyama, Table of n, a(n) for n = 1..1000

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