OFFSET

1,6

FORMULA

Generate the prime sequence with primes labeled 1 mod 4 or 3 mod 4. Add count of primes to sequence if just 9 primes occur before interruption by a prime congruent to 3 mod 4.

EXAMPLE

a(6)=6 because 6 sets of 9 primes occur below 10^6, each run interrupted by a prime congruent to 3 mod 4.

CROSSREFS

KEYWORD

more,nonn

AUTHOR

Enoch Haga, Mar 02 2004

EXTENSIONS

a(9) from Rick L. Shepherd, Jul 15 2009

a(10) from Sean A. Irvine, Oct 25 2011

a(11) from Chai Wah Wu, Mar 18 2018

STATUS

approved