OFFSET
1,1
LINKS
J. K. Andersen, Consecutive Congruent Primes.
EXAMPLE
a(4) = 79063 because this number is the first in a sequence of 4 consecutive primes all of the form 8n + 7.
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 ] != {7}, k = NextPrime[ k ]; a = Take[ AppendTo[ a, Mod[ k, 8 ]], -n ]]; p = NestList[ PrevPrime, k, n ]; Print[ p[[ -2 ] ]]; p = p[[ -1 ]], {n, 1, 8} ] a(9) > 115647000.
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Oct 10 2000
EXTENSIONS
More terms from Jens Kruse Andersen, May 28 2006
a(17) from Giovanni Resta, Aug 04 2013
STATUS
approved