A121242 Number of 2's in first n primes.

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, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 7, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 24, 24, 24, 24, 24

Offset: 1

Author

Zak Seidov, Aug 22 2006

Keywords

• base
• nonn

Comments

In the first 10^m (m=3,4,5) primes there are 339, 4070, 55213 2's, among all 3803, 48982, 610484 digits, which gives the frequencies {0.08914, 0.08309, 0.09044}.

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A068670 Number of digits in the first n primes.

Partial sums of A085976.

Programs

Maple

ListTools:-PartialSums([seq(numboccur(2,convert(ithprime(i),base,10)),i=1..100)]); # Robert Israel, Jun 13 2018

Mathematica

Accumulate[DigitCount[Prime[Range[90]],10,2]] (* Harvey P. Dale, Nov 09 2013 *)