A068150
First of n consecutive primes == 7 mod 10.
Original entry on oeis.org
7, 337, 1627, 57427, 192637, 776257, 15328637, 70275277, 244650317, 452942827, 452942827, 73712513057, 319931193737, 2618698284817, 10993283241587, 54010894438097, 101684513099627, 196948379177587
Offset: 1
a(3) = 1627 as it is the start of the first occurrence of the three consecutive prime 1627, 1637 and 1657 ending in 7.
More terms from Larry Reeves (larryr(AT)acm.org), Jun 14 2002
More terms from
Enoch Haga, Jan 17 2004. a(12) is from Phil Carmody.
A057636
Initial prime in first sequence of n primes congruent to 4 modulo 5. The first prime in a sequence of length n all ending with the digit 9.
Original entry on oeis.org
19, 139, 3089, 18839, 123229, 2134519, 12130109, 23884639, 363289219, 9568590299, 24037796539, 130426565719, 405033487139, 3553144754209, 4010803176619, 71894236537009, 71894236537009
Offset: 1
a(5) = 123229 because this number is the first in a sequence of 5 consecutive primes all of the form 5n + 4.
-
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 ] != {4}, k = NextPrime[ k ]; a = Take[ AppendTo[ a, Mod[ k, 5 ] ], -n ] ]; p = NestList[ PrevPrime, k, n ]; Print[ p[ [ -2 ] ] ]; p = p[ [ -1 ] ], {n, 1, 9} ]
Phil Carmody gives a(15)= 4010803176619 in
A054681
Showing 1-2 of 2 results.
Comments