This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A243400 Primes p such that p^6 - p^5 - p^4 - p^3 - p^2 - p - 1 is prime. 0
 5, 7, 17, 37, 79, 157, 239, 269, 277, 359, 419, 449, 467, 557, 677, 739, 787, 829, 857, 977, 1319, 1399, 1597, 1657, 2069, 2269, 2297, 2377, 2437, 2459, 2819, 2969, 2999, 3019, 3137, 3299, 3389, 3407, 3967, 4007, 4099, 4357, 4547, 4729, 4987, 5179, 5419, 5569, 5779, 6637 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(1) = 5 is the only term that ends in a 5. It is unknown if any term will end in a 3 or 1. LINKS EXAMPLE 5 is prime and 5^6 - 5^5 - 5^4 - 5^3 - 5^2 - 5 - 1 = 11719 is prime. Thus 5 is a member of this sequence. PROG (Python) import sympy from sympy import isprime {print(n, end=', ') for n in range(10**4) if isprime(n**6-n**5-n**4-n**3-n**2-n-1) and isprime(n)} (PARI) for(n=1, 10^4, if(ispseudoprime(n)&&ispseudoprime(n^6-sum(i=0, 5, n^i)), print1(n, ", "))) CROSSREFS Cf. A243300. Sequence in context: A272717 A018538 A038968 * A318568 A239414 A163570 Adjacent sequences:  A243397 A243398 A243399 * A243401 A243402 A243403 KEYWORD nonn AUTHOR Derek Orr, Jun 04 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 12 10:19 EST 2019. Contains 329953 sequences. (Running on oeis4.)