A243962 - OEIS

A243962

Primes p such that 10p + 1, 100p + 1 and 1000p + 1 are also primes.

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

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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: A060211 A355329 A133029 * A287304 A023984 A360400

Adjacent sequences: A243959 A243960 A243961 * A243963 A243964 A243965

KEYWORD

nonn

AUTHOR

K. D. Bajpai, Jun 16 2014

STATUS

approved