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A073516 Number of primes less than 10^n with initial digit 2. 2
1, 3, 19, 146, 1129, 9142, 77025, 664277, 5837665, 52064915, 469864125, 4281198201, 39319600765, 363545360347, 3380562309312, 31590949437540, 296487794277035, 2793170342851930, 26402713858800478, 250324979315879678, 2379753569255122805, 22678735843184786383 (list; graph; refs; listen; history; text; internal format)
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 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

a(21)-a(22) added by David Baugh, Mar 21 2015

STATUS

approved

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Last modified December 9 12:25 EST 2016. Contains 278971 sequences.