OFFSET
1,2
EXAMPLE
a(4) = 1252; a(4) = Sum_{k=1..4} (4^k)' = (4^1)' + (4^2)' + (4^3)' + (4^4)' = 4' + 16' + 64' + 256' = 4 + 32 + 192 + 1024 = 1252.
MAPLE
a:= n-> add(n^k*add(i[2]/i[1], i=ifactors(n^k)[2]), k=1..n):
seq(a(n), n=1..19); # Alois P. Heinz, Oct 15 2021
MATHEMATICA
d[0] = d[1] = 0; d[n_] := n * Plus @@ ((Last[#]/First[#]) & /@ FactorInteger[n]); a[n_] := Sum[d[n^k], {k, 1, n}]; Array[a, 20] (* Amiram Eldar, Oct 16 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Oct 15 2021
STATUS
approved