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”).

a(n) is the number of n-digit primes that have at least one zero among their digits (A056709).
0

%I #22 Jun 01 2024 06:21:40

%S 0,0,15,204,2251,23715,240528,2391394,23540109,230318080,2244729936,

%T 21819401038,211711461260,2051836712085

%N a(n) is the number of n-digit primes that have at least one zero among their digits (A056709).

%F a(n) = A091644(n) - A091644(n-1) for n > 1. - _Michael S. Branicky_, May 31 2024

%e For n = 3, the 3-digit prime numbers that have the digit 0 are 101, 103, 107, 109, 307, 401, 409, 503, 509, 601, 607, 701, 709, 809 and 907. Therefore, a(3) = 15.

%o (PARI) a(n) = my(s=0); forprime(p=10^(n-1), 10^n-1, if (vecmin(digits(p)) == 0, s++)); s; \\ _Michel Marcus_, May 31 2024

%Y First differences of A091644.

%Y Cf. A000040, A006879, A056709.

%K nonn,base,more

%O 1,3

%A _Gonzalo Martínez_, May 30 2024

%E More terms (using A091644) from _Michael S. Branicky_, May 30 2024