A067199 Integers k such that k*28*c + 1 is prime for c = 1, 2, 4, 7 and 14.

2136, 2211, 4071, 5106, 5430, 9000, 10656, 17655, 18315, 20220, 20805, 21381, 22356, 22920, 23025, 29616, 37050, 39261, 45795, 49920, 55686, 60435, 62205, 64380, 79356, 81345, 91455, 94800, 95910, 96285, 105336, 108585, 111885, 118626

Offset: 1

Author

Frank Ellermann, Feb 19 2002

Keywords

• nonn
• easy

Comments

The product of the 5 primes is a Carmichael number. 28=1+2+4+7+14.

Examples

			2136 results in Carmichael number 599966117492747584686619009.
		

References

• H. Davenport, The Higher Arithmetic. Cambridge Univ. Press, 7th ed., 1999, exercise 8.4.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A002997, A046025 (based on 6 instead of 28, exercise 8.3 in Davenport), A112428.

Programs

Mathematica

aQ[n_] := AllTrue[{1, 2, 4, 7, 14}, PrimeQ[28 * n * # + 1] &]; Select[Range[10^5], aQ] (* Amiram Eldar, Sep 19 2019 *)

Extensions

Offset corrected by Amiram Eldar, Sep 19 2019