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A243962 Primes p such that 10p + 1, 100p + 1 and 1000p + 1 are also primes. 1
7, 13, 19, 103, 823, 1021, 1579, 1867, 2503, 3331, 5779, 6871, 6949, 9007, 10093, 10399, 11317, 11743, 13327, 13381, 15859, 16657, 17539, 17659, 22189, 26317, 26557, 26821, 27397, 27943, 29209, 29383, 30211, 32443, 37309, 38287, 40213, 40507, 44497, 47569, 47977 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

K. D. Bajpai, Table of n, a(n) for n = 1..10000

EXAMPLE

7 is in the sequence because 7 is prime, 10*7 + 1 = 71 is prime, 100*7 + 1 = 701 is prime, and 1000*7 + 1 = 7001 is prime.

MAPLE

with(numtheory):A243962:= proc() local p; p:=ithprime(n); if isprime(10*p+1) and isprime(100*p+1) and isprime(1000*p+1) then RETURN (p); fi; end: seq(A243962 (), n=1..5000);

MATHEMATICA

Select[Prime[Range[10000]], PrimeQ[10 # + 1] && PrimeQ[100 # + 1] && PrimeQ[1000 # + 1] &]

CROSSREFS

Cf. A000040, A023237, A024912.

Sequence in context: A070850 A060211 A133029 * A287304 A023984 A308200

Adjacent sequences:  A243959 A243960 A243961 * A243963 A243964 A243965

KEYWORD

nonn

AUTHOR

K. D. Bajpai, Jun 16 2014

STATUS

approved

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Last modified November 14 17:24 EST 2019. Contains 329126 sequences. (Running on oeis4.)