Partial sums of A046719(n) = n*A006879(n). In other words, a(n) is the number of digits used in writing out all {A006880(n)} primes below 10^n. - Lekraj Beedassy, Dec 13 2007
There are 25 primes < 100; 4 of them are 1-digit numbers and 21 are 2-digit numbers. Thus a(2) = 4 + 21*2 = 46.
MATHEMATICA
Accumulate[Table[n(PrimePi[10^n]-PrimePi[10^(n-1)]), {n, 0, 14}]] (* This generates the first 15 terms of the sequence, but if n exceeds 14 the function PrimePi in Mathematica cannot calculate it. *) (* Harvey P. Dale, Jun 13 2014 *)
