OFFSET
1,1
COMMENTS
All the positive numbers of the form -(x^2 - 21*x + 1) are primes. Compare A335984.
REFERENCES
T. Özsoy, Visualization of Prime Numbers: Twin Prime Numbers, Ozsoy Triangle and Ozsoy Series, in A. Baki, B. Güven, and M. Güler, editors, Proc. 4th International Symposium of Turkish Computer and Mathematics Education, 26-Sep 28 2019, İzmir; pages 678-688.
LINKS
FORMULA
G.f.: (x^2 + 20*x - 19)/(x - 1)^3. - Jinyuan Wang, Jul 08 2020
MATHEMATICA
Table[-n^2+21n-1, {n, 60}] (* or *) LinearRecurrence[{3, -3, 1}, {19, 37, 53}, 60] (* Harvey P. Dale, Mar 07 2023 *)
PROG
(PARI) a(n)=-n^2+21*n-1 \\ Charles R Greathouse IV, Oct 21 2022
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Tamer Özsoy, Jul 02 2020
STATUS
approved