OFFSET
1,2
FORMULA
EXAMPLE
a(1) = 1 because the first 10 primes are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, among which there is only one prime ending in 1.
PROG
(PARI) a(n) = #select(x->((x % 10) == 1), primes(10^n)); \\ Michel Marcus, Mar 07 2018
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
G. L. Honaker, Jr., Mar 05 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
STATUS
approved