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A073514 Number of primes less than 10^n with initial digit 4. 23
0, 3, 20, 139, 1069, 8747, 74114, 641594, 5661135, 50653546, 458352691, 4185483176, 38510936699, 356622729564, 3320632228693, 31067060521057, 291869049531878, 2752144407792176, 26035873192178041, 247025281876786013, 2349914303292170310, 22407593754131275705 (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 4 (namely 41, 43 and 47).

MATHEMATICA

f[n_] := f[n] = PrimePi[5*10^n] - PrimePi[4*10^n] + f[n - 1]; f[0] = 0; 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: A114479 A074574 A267899 * A163065 A082143 A009156

Adjacent sequences:  A073511 A073512 A073513 * A073515 A073516 A073517

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

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Last modified January 21 10:26 EST 2020. Contains 331105 sequences. (Running on oeis4.)