A194194 Primes of the form n^6 + n^5 + n^4 + n^3 + n^2 + n + 1 where n is nonprime.

7, 55987, 8108731, 321272407, 3092313043, 4201025641, 9684836827, 31401724537, 47446779661, 83925549247, 100343116693, 141276239497, 265462278481, 438668366137, 654022685443, 742912017121, 2333350772341, 3324554405047, 4033516174507, 4432676798593, 9752186278927, 14505760086637, 15656690128843, 16882733081761

Offset: 1

Author

Jonathan Vos Post, Dec 20 2012

Keywords

• nonn
• easy

Comments

Subset of A088550. The n in A018252 for which n^6 + n^5 + n^4 + n^3 + n^2 + n + 1 are prime begin 1, 6, 14, 26, 38, 40.

Examples

			a(1) = 1^6 + 1^5 + 1^4 + 1^3 + 1^2 + 1 + 1 = 7.
a(2) = 6^6 + 6^5 + 6^4 + 6^3 + 6^2 + 6 + 1 = 55987.
a(3) = 14^6 + 14^5 + 14^4 + 14^3 + 14^2 + 14 + 1 = 8108731.
a(4) = 26^6 + 26^5 + 26^4 + 26^3 + 26^2 + 26 + 1 = 321272407.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf, A000040, A018252, A088548, A185632, A192321.

Programs

Mathematica

With[{nn=200},Select[Total[#^Range[0,6]]&/@Complement[Range[nn], Prime[ Range[PrimePi[nn]]]],PrimeQ]] (* Harvey P. Dale, Nov 15 2013 *)