A123200 Numbers k such that 1000000*k-1 and 1000000*k+1 are twin primes.

24, 30, 198, 345, 348, 432, 438, 471, 492, 609, 669, 774, 777, 858, 864, 1032, 1083, 1125, 1218, 1395, 1536, 1824, 1914, 1929, 2088, 2139, 2301, 2334, 2376, 2418, 2448, 2460, 2544, 2763, 2832, 2970, 3021, 3297, 3369, 3384, 3495, 3528, 3540, 3633, 3777

Offset: 1

Author

Jonathan Vos Post, Nov 05 2006

Keywords

• easy
• nonn
• less

Examples

			a(6) = 432 because 431999999 and 432000001 are primes.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..2000

Crossrefs

Cf. A000040, A040040, A045753, A002822, A124065.

Programs

Maple

a:=proc(n) if isprime(10^6*n-1)=true and isprime(10^6*n+1)=true then n else fi end: seq(a(n),n=1..4500); # Emeric Deutsch, Nov 16 2006

Mathematica

Select[Range[3800],AllTrue[#*10^6+{1,-1},PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Nov 13 2017 *)

Extensions

More terms from Emeric Deutsch, Nov 16 2006