

A073516


Number of primes less than 10^n with initial digit 2.


0



1, 3, 19, 146, 1129, 9142, 77025, 664277, 5837665, 52064915, 469864125, 4281198201, 39319600765, 363545360347, 3380562309312, 31590949437540, 296487794277035, 2793170342851930, 26402713858800478, 250324979315879678
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OFFSET

1,2


LINKS

Table of n, a(n) for n=1..20.
Thomas R. Nicely, Some Results of Computational Research in Prime Numbers


EXAMPLE

a(2)=3 because there are 3 primes up to 10^2 whose initial digit is 2 (namely 2, 23 and 29).


MATHEMATICA

f[n_] := f[n] = PrimePi[3*10^n]  PrimePi[2*10^n] + f[n  1]; f[0] = 1; Table[ f[n], {n, 0, 13}]


CROSSREFS

Cf. A073509 to A073517, their sum is A006880.
Sequence in context: A058859 A095002 A080833 * A005258 A131551 A074546
Adjacent sequences: A073513 A073514 A073515 * A073517 A073518 A073519


KEYWORD

base,hard,nonn


AUTHOR

Shyam Sunder Gupta, Aug 14 2002


EXTENSIONS

Edited and extended by Robert G. Wilson v, Aug 29 2002


STATUS

approved



