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A073511
Number of primes less than 10^n with initial digit 7.
23
1, 4, 18, 125, 1027, 8435, 71564, 622882, 5516130, 49495432, 448855139, 4106164356, 37838546363, 350849788546, 3270531245684, 30628143485953, 287992070079777, 2717649138419586, 25726964404879666, 244242934202964444, 2324722877951987037, 22178433287546997612
OFFSET
1,2
LINKS
Thomas R. Nicely, Some Results of Computational Research in Prime Numbers [See local copy in A007053]
Tomás Oliveira e Silva, Tables of values of pi(x) and of pi2(x)
EXAMPLE
a(2)=4 because there are 4 primes up to 10^2 whose initial digit is 7 (namely 7, 71, 73 and 79).
MATHEMATICA
f[n_] := f[n] = PrimePi[8*10^n] - PrimePi[7*10^n] + f[n - 1]; f[0] = 1; Table[ f[n], {n, 0, 12}]
CROSSREFS
KEYWORD
base,hard,nonn
AUTHOR
Shyam Sunder Gupta, Aug 14 2002
EXTENSIONS
Edited and extended by Robert G. Wilson v, Aug 29 2002
a(20)-a(22) added by David Baugh, Mar 22 2015
STATUS
approved