A136364 a(n) = Sum_{ composite k, 1 <= k <= 10^n} (Number of divisors d of k with 1 < d < k).
8, 283, 5070, 73669, 966751, 11970035, 142725365, 1657511569, 18877697635, 211802823221, 2348286736298, 25785452449087, 280880375389758, 3039062263181055, 32693207724724247, 349957928177109417, 3729837791070240369, 39600963003695964401, 419035480966899467509
Offset: 1
Keywords
Examples
a(1) = 8 because there are 8 distinct divisors of composite numbers k through 10^1; these are for 4(1); 6(2); 8(2); 9(1); 10(2); and 1 + 2 + 2 + 1 + 2 = 8.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..36 (calculated using the b-file at A057494)
Formula
a(n) = A057494(n) - 2*10^n + 1. - Max Alekseyev, May 10 2009
Extensions
Edited by N. J. A. Sloane, Jan 12 2008
Three more terms from Max Alekseyev, May 10 2009
a(10)-a(16) from Max Alekseyev, Jan 25 2010
a(17)-a(19) from Amiram Eldar, Aug 05 2024