A065682 Number of primes <= prime(n) which begin with a 3.

0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19

Offset

1,11

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Example

a(1) = 0, a(2) = 1. a(664579) = 75290 (A000040(664579) = 9999991 is the largest prime < 10^7).

Mathematica

Accumulate@ Array[Boole[First@ IntegerDigits@ Prime@ # == 3] &, 87] (* Michael De Vlieger, Jun 14 2018 *)

Prog

(PARI) lista(n) = { my(a=[p\10^logint(p, 10)==3 | p<-primes(n)]); for(i=2, #a, a[i]+=a[i-1]); a} \\ Harry J. Smith, Oct 26 2009

Crossrefs

Cf. A000040, A045709, A065680.

Sequence in context: A157532 A065684 A065683 * A065681 A121242 A185436

Adjacent sequences: A065679 A065680 A065681 * A065683 A065684 A065685

Keyword

base,nonn

Author

Reinhard Zumkeller, Nov 13 2001

Status

approved