|
%I #5 Apr 20 2018 00:58:28
%S 3,7,15,26,57,128,319,849,2285,6395,18072,51914,150497,439554,1292568,
%T 3819778,11341738,33806234,101113152,303345648,912494104,2751564993,
%U 8315282765,25179029388,76381806785,232094778772,706331084162,2152626447195,6569037508556
%N a(n) is the number of n-digit proper prime powers.
%C First differences of A267574.
%F a(n) = A267574(n) - A267574(n-1).
%e a(1) = 3 because there are 3 1-digit proper prime powers: 2^2 = 4, 2^3 = 8, and 3^2 = 9.
%e a(2) = 7 because there are 7 2-digit proper prime powers: 2^4 = 16, 2^5 = 32, 2^6 = 64; 3^3 = 27, 3^4 = 81; 5^2 = 25; and 7^2 = 49.
%Y Cf. A267574.
%K nonn,base
%O 1,1
%A _Jon E. Schoenfield_, Apr 19 2018
|
