A057644 Initial prime in first sequence of n primes congruent to 1 modulo 9.

19, 523, 15823, 655453, 19256491, 24084793, 303392377, 3408167431, 17875882441, 179445819277, 1563518842687

Offset

1,1

Links

Table of n, a(n) for n=1..11.

J. K. Andersen, Consecutive Congruent Primes.

Example

a(3) = 15823 because this number is the first in a sequence of 3 consecutive primes all of the form 9n + 1.

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 ] != {1}, k = NextPrime[ k ]; a = Take[ AppendTo[ a, Mod[ k, 9 ] ], -n ] ]; p = NestList[ PrevPrime, k, n ]; Print[ p[ [ -2 ] ] ]; p = p[ [ -1 ] ], {n, 1, 7} ] a(8) > 1655036000.

Crossrefs

Sequence in context: A243784 A158583 A009081 * A283382 A196512 A027406

Adjacent sequences: A057641 A057642 A057643 * A057645 A057646 A057647

Keyword

nonn

Author

Robert G. Wilson v, Oct 11 2000

Extensions

More terms from Jens Kruse Andersen, May 31 2006

Status

approved