A300400 a(n) = number of primes that end in 9 among the first 10^n primes.

2, 24, 246, 2491, 25009, 249940, 2499751, 25000026, 249997694, 2499999305, 24999974939, 249999962302

Offset: 1

Author

G. L. Honaker, Jr., Mar 05 2018

Keywords

• nonn
• base
• more

Examples

			a(1) = 2 because the first 10 primes are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, among which there are two primes ending in 9.
		

Links

• Caldwell and Honaker, Prime Curios!

Crossrefs

Cf. A006988, A030433, A185715, A300397, A300398, A300399.

Programs

PARI

a(n) = #select(x->((x % 10) == 9), primes(10^n)); \\ Michel Marcus, Mar 07 2018

Formula

a(n) = A185715(A006988(n)). - Michel Marcus, Mar 20 2018

Extensions

a(3)-a(8) from Chuck Gaydos

a(9) from Jon E. Schoenfield, Mar 20 2018

a(10)-a(12) from Giovanni Resta, Mar 27 2018