OFFSET
1,1
LINKS
Michel Marcus, Table of n, a(n) for n = 1..10000
FORMULA
a(n) ~ (1 + A064859) * n. - Amiram Eldar, Jul 11 2021
EXAMPLE
If b(n) is least non-divisor of n then, a(6) = b(1)+b(2)+b(3)+b(4)+b(5)+b(6) => 2+3+2+3+2+4 = 16.
MATHEMATICA
lnd[n_] := Module[{k = 2}, While[Divisible[n, k], k++]; k]; Accumulate @ Array[lnd, 100] (* Amiram Eldar, Jul 11 2021 *)
PROG
(PARI) f(n) = {my(k=2); while(!(n % k), k++); k; } \\ A007978
a(n) = sum(k=1, n, f(k)); \\ Michel Marcus, Jul 11 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Shobhit Tewari, Jul 09 2021
STATUS
approved