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A321675
a(n) = Sum_{k=1..10^n} k*sigma(k).
0
1, 622, 558275, 549175530, 548429473046, 548320905633448, 548312690631798482, 548311465139943768941, 548311366911386862908968, 548311356554322895313137239, 548311355740964925044531454428, 548311355626818302486560961291870, 548311355617569600726982364186141942
OFFSET
0,2
FORMULA
a(n) = A143128(10^n).
a(n) ~ 10^(3*n) * Pi^2 / 18.
MATHEMATICA
Array[Sum[k DivisorSigma[1, k], {k, 10^#}] &, 7, 0] (* Michael De Vlieger, Nov 20 2018 *)
PROG
(PARI) a(n) = sum(k=1, 10^n, k*sigma(k)); \\ Michel Marcus, Nov 23 2018
CROSSREFS
Sequence in context: A207315 A206698 A268018 * A371695 A345556 A345810
KEYWORD
nonn
AUTHOR
Daniel Suteu, Nov 16 2018
STATUS
approved