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 A073515 Number of primes less than 10^n with initial digit 3. 23
 1, 3, 19, 139, 1097, 8960, 75290, 651085, 5735086, 51247361, 463196868, 4225763390, 38851672813, 359541975662, 3345924530873, 31288310624754, 293820812588401, 2769490109678920, 26191046215879444, 248421640738371325, 2362546444095790527, 22522418647770393663 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Thomas R. Nicely, Some Results of Computational Research in Prime Numbers Tomás Oliveira e Silva, Tables of values of pi(x) and of pi2(x) EXAMPLE a(2)=3 because there are 3 primes up to 10^2 whose initial digit is 3 (namely 3, 31 and 37). MATHEMATICA f[n_] := f[n] = PrimePi[4*10^n] - PrimePi[3*10^n] + f[n - 1]; f[0] = 1; Table[ f[n], {n, 0, 12}] CROSSREFS Cf. A073509 to A073517, their sum is A006880. For primes with initial digit d (1 <= d <= 9) see A045707, A045708, A045709, A045710, A045711, A045712, A045713, A045714, A045715; A073517, A073516, A073515, A073514, A073513, A073512, A073511, A073510, A073509 Sequence in context: A115750 A156894 A221374 * A074559 A027314 A025571 Adjacent sequences:  A073512 A073513 A073514 * A073516 A073517 A073518 KEYWORD nonn,base,hard AUTHOR Shyam Sunder Gupta, Aug 14 2002 EXTENSIONS Edited and extended by Robert G. Wilson v, Aug 29 2002 a(21)-a(22) added by David Baugh, Mar 22 2015 STATUS approved

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Last modified January 29 08:04 EST 2020. Contains 331337 sequences. (Running on oeis4.)