login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

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
OFFSET
1,2
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: A247788 A355598 A006759 * A074524 A212280 A360581
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