OFFSET
1,1
LINKS
J. K. Andersen, Consecutive Congruent Primes.
EXAMPLE
a(3) = 2243 because this number is the first in a sequence of 3 consecutive primes all of the form 8n + 3.
MATHEMATICA
NextPrime[ n_Integer ] := Module[ {k = n + 1}, While[ ! PrimeQ[ k ], k++ ]; Return[ k ] ]; PrevPrime[ n_Integer ] := Module[ {k = n - 1}, While[ ! PrimeQ[ k ], k-- ]; Return[ k ] ]; p = 0; Do[ a = Table[ -1, {n} ]; k = Max[ 1, p ]; While[ Union[ a ] != {3}, k = NextPrime[ k ]; a = Take[ AppendTo[ a, Mod[ k, 8 ] ], -n ] ]; p = NestList[ PrevPrime, k, n ]; Print[ p[ [ -2 ] ] ]; p = p[ [ -1 ] ], {n, 1, 9} ] a(9) > 305256000.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert G. Wilson v, Oct 10 2000
EXTENSIONS
More terms from Jens Kruse Andersen, May 28 2006
a(16)-a(18) from Giovanni Resta, Aug 04 2013
a(19)-a(20) from Martin Ehrenstein, May 28 2023
STATUS
approved