A337480 Numbers k such that exactly one of 6*k + 5 and 12*k + 5 is prime.

6, 12, 13, 17, 18, 19, 23, 26, 27, 28, 31, 33, 39, 41, 44, 47, 48, 49, 52, 53, 54, 56, 57, 59, 67, 68, 69, 74, 76, 78, 83, 86, 87, 88, 91, 93, 94, 97, 101, 109, 112, 114, 116, 117, 124, 126, 128, 129, 132, 133, 137, 139, 141, 144, 146, 147, 151, 154, 159, 161

Offset

1,1

Links

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

Example

a(5) = 18 is a term because 6*18 + 5 = 113 is prime; but 12*18 + 5 = 221 = (13*17) is a composite number.
a(8) = 26 is a term because 6*26 + 5 = 161 = (7*23) is a composite number; but 12*26 + 5 = 317 is prime.

Maple

A337480:=k->`if`(isprime(6*k+5) xor isprime(12*k+5), k, NULL): seq(A337480(k), k=1..1000);

Mathematica

Select[Range[0, 250], Xor[PrimeQ[6 # + 5], PrimeQ[12 # + 5]] &]

Prog

(PARI) for(k=1, 1000, if (bitxor(isprime(6*k+5), isprime(12*k+5)), print1(k, ", ")));

Crossrefs

Cf. A063913, A145487, A145490, A172287.

Sequence in context: A335485 A004749 A107687 * A297258 A296702 A297135

Adjacent sequences: A337477 A337478 A337479 * A337481 A337482 A337483

Keyword

nonn

Author

K. D. Bajpai, Aug 28 2020

Status

approved