%I A073511
%S A073511 1,4,18,125,1027,8435,71564,622882,5516130,49495432,448855139,
%T A073511 4106164356,37838546363,350849788546,3270531245684,30628143485953,
%U A073511 287992070079777,2717649138419586,25726964404879666
%N A073511 Number of primes less than 10^n with initial digit 7.
%H A073511 Thomas R. Nicely, <a href="http://www.trnicely.net/index.html">Some Results 
               of Computational Research in Prime Numbers</a>
%e A073511 a(2)=4 because there are 4 primes up to 10^2 whose initial digit is 7 
               (namely 7, 71, 73 and 79).
%t A073511 f[n_] := f[n] = PrimePi[8*10^n] - PrimePi[7*10^n] + f[n - 1]; f[0] = 
               1; Table[ f[n], {n, 0, 12}]
%Y A073511 Cf. A073509 to A073517, their sum is A006880.
%Y A073511 Sequence in context: A005442 A084661 A112294 this_sequence A108704 A001423 
               A158341
%Y A073511 Adjacent sequences: A073508 A073509 A073510 this_sequence A073512 A073513 
               A073514
%K A073511 base,hard,nonn
%O A073511 1,2
%A A073511 Shyam Sunder Gupta (guptass(AT)rediffmail.com), Aug 14 2002
%E A073511 Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 29 
               2002