OFFSET
1,1
COMMENTS
This sequence gives 168 prime numbers for n=1 to 168 with 63 different primes. This formula is based on the lucky numbers of Euler.
LINKS
Frederic Isenmann, Table of n, a(n) for n=1..168.
EXAMPLE
For n = 23, a(23) = 17^2+17+41 = 347, and 347 is prime.
MATHEMATICA
Table[#^2 + # + 41 &@ Mod[2097203 , n], {n, 54}] (* Michael De Vlieger, Feb 12 2017 *)
f[n_]:=Module[{x=Mod[2097203, n]}, x^2+x+41]; Array[f, 60] (* Harvey P. Dale, Jul 28 2017 *)
PROG
(Python)
def formul(i):
return ((i*i+2097203)%i)*((i*i+2097203)%i)+((i*i+2097203)%i)+41
for i in range(1, 169):
n=formul(i)
print(n, end=", ")
(PARI) a(n)=subst(x^2+x+41, x, 2097203%n) \\ Charles R Greathouse IV, Feb 14 2017
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Frederic Isenmann, Feb 11 2017
STATUS
approved