

A073513


Number of primes less than 10^n with initial digit 5.


23



1, 3, 17, 131, 1055, 8615, 72951, 633932, 5602768, 50193913, 454577490, 4153943134, 38243708524, 354330372215, 3300752009165, 30892997367352, 290332329192655, 2738477783884855, 25913537508233527, 245923809778144431, 2339944887042508496, 22316931815316988517
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OFFSET

1,2


LINKS

Table of n, a(n) for n=1..22.
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 5 (namely 5, 53 and 59).


MATHEMATICA

f[n_] := f[n] = PrimePi[6*10^n]  PrimePi[5*10^n] + f[n  1]; f[0] = 1; Table[ f[n], {n, 0, 13}]


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: A328402 A247788 A006759 * A074524 A212280 A307680
Adjacent sequences: A073510 A073511 A073512 * A073514 A073515 A073516


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



