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A346028 Primes that are the first in a run of exactly 8 emirps. 2
334759, 9094009, 9685771, 11875307, 12503017, 19776443, 32906869, 35414443, 37376201, 70252333, 71161309, 73694129, 77454067, 93907523, 98606489, 100545637, 104827991, 112604857, 147009703, 155376791, 183766217, 187717499, 194024953, 196702423, 314716411 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
There are large gaps in this sequence because all terms need to begin with 1, 3, 7, or 9 otherwise the reversal is composite.
LINKS
EXAMPLE
a(1) = 334759 because of the 10 consecutive primes 334753, 334759, 334771, 334777, 334783, 334787, 334793, 334843, 334861, 334877 all except 334753 and 334877 are emirps and this is the first such occurrence.
MATHEMATICA
EmQ[n_]:=(s=IntegerReverse@n; PrimeQ@s&&n!=s);
Monitor[Do[p=Prime@k; If[MemberQ[{1, 3, 7, 9}, First@IntegerDigits@p], If[Boole[EmQ/@NextPrime[p, Range[-1, 8]]]=={0, 1, 1, 1, 1, 1, 1, 1, 1, 0}, Print@p]], {k, 10^6}], p] (* Giorgos Kalogeropoulos, Jul 27 2021 *)
PROG
(Python) # uses code in A346026
print(aupto(10**7, runlength=8)) # Michael S. Branicky, Jul 14 2021
CROSSREFS
Subsequence of A006567 (emirps).
Sequence in context: A261861 A234129 A232412 * A268280 A234081 A022225
KEYWORD
nonn,base
AUTHOR
Lars Blomberg, Jul 14 2021
STATUS
approved

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Last modified February 20 17:05 EST 2024. Contains 370213 sequences. (Running on oeis4.)