A073516 Number of primes less than 10^n with initial digit 2.

1, 3, 19, 146, 1129, 9142, 77025, 664277, 5837665, 52064915, 469864125, 4281198201, 39319600765, 363545360347, 3380562309312, 31590949437540, 296487794277035, 2793170342851930, 26402713858800478, 250324979315879678, 2379753569255122805, 22678735843184786383

Offset

1,2

Links

Table of n, a(n) for n=1..22.

Thomas R. Nicely, Some Results of Computational Research in Prime Numbers [See local copy in A007053]

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.

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: A095002 A293527 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