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A210514 Prime numbers generated by concatenating N, N, and 9. 1
229, 449, 11119, 14149, 22229, 28289, 31319, 37379, 44449, 49499, 52529, 56569, 67679, 70709, 71719, 80809, 86869, 89899, 94949, 95959, 1061069, 1101109, 1131139, 1151159, 1161169, 1191199 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This series is similar to A030458 and A052089

Base considered is 10

LINKS

Table of n, a(n) for n=1..26.

EXAMPLE

for n=2, a(1)= 229.

for n=4, a(2)= 449.

for n=11, a(3)= 11119.

for n=14, a(4)= 14149.

MATHEMATICA

Select[Table[FromDigits[Flatten[Join[IntegerDigits/@{n, n}, {9}]]], {n, 200}], PrimeQ] (* Harvey P. Dale, Apr 23 2015 *)

PROG

(Python)

import numpy as np

def factors(n):

....return reduce(list.__add__, ([i, n//i] for i in range(1, int(n**0.5) + 1) if n % i == 0))

for i in range(1, 2000):

....p1=int(str(i)+str(i)+"1")

....if len(factors(p1))<3:

........print p1

CROSSREFS

Cf. A030458, A052089.

Sequence in context: A139512 A142263 A142608 * A142665 A124684 A178673

Adjacent sequences:  A210511 A210512 A210513 * A210515 A210516 A210517

KEYWORD

base,nonn,easy

AUTHOR

Abhiram R Devesh, Jan 26 2013

STATUS

approved

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Last modified December 16 04:19 EST 2018. Contains 318158 sequences. (Running on oeis4.)