A241485 Primes p such that p+2, p+222 and p+2222 are also prime.

17, 29, 59, 71, 281, 461, 827, 1151, 1277, 1289, 1487, 1667, 1877, 1931, 2687, 2789, 2801, 3359, 3557, 3851, 4049, 4229, 4259, 4481, 4649, 5417, 5519, 5657, 5867, 5879, 6089, 6131, 6299, 6359, 6779, 6791, 7127, 7211, 8291, 8837, 9719, 10067, 10937, 13397, 13679

Offset

1,1

Comments

All the terms in the sequence are congruent to 2 mod 3.

The constants in the definition (2, 222 and 2222) are the concatenation of digit 2.

Links

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

Example

a(1) = 17 is a prime: 17+2 = 19, 17+222 = 239 and 17+2222 = 2239 are also prime.
a(2) = 29 is a prime: 29+2 = 31, 29+222 = 251 and 29+2222 = 2251 are also prime.

Maple

KD:= proc() local a, b, d, e; a:= ithprime(n); b:=a+2; d:=a+222; e:=a+2222; if isprime(b)and isprime(d)and isprime(e)  then return (a) :fi; end: seq(KD(), n=1..5000);

Mathematica

KD={}; Do[p=Prime[n]; If[PrimeQ[p+2]&&PrimeQ[p+222]&&PrimeQ[p+2222], AppendTo[KD, p]], {n, 5000}]; KD
(*For b-file*) c=0; p=Prime[n]; Do[If[PrimeQ[p+2]&&PrimeQ[p+222]&&PrimeQ[p+2222], c=c+1; Print[c, "  ", p]], {n, 1, 3*10^6}];

Crossrefs

Cf. A000040, A023200, A046136, A230223, A236302, A237890.

Sequence in context: A090796 A342820 A190556 * A089629 A007349 A154616

Adjacent sequences: A241482 A241483 A241484 * A241486 A241487 A241488

Keyword

nonn

Author

K. D. Bajpai, Apr 23 2014

Status

approved