A188424 - OEIS

%I #12 Apr 14 2018 13:09:21

%S 1,2,4,4,2,10,4,3,16,6,5,10,10,5,13,14,3,10,16,7,40,8,6,26,12,9,19,14,

%T 9,34,21,5,19,36,13,28,18,7,31,18,19,34,15,14,27,27,11,41,31,11,68,16,

%U 10,71,30,20,23,21,16,40,40,13,57,37,23,37,24,16,67,44,16,41,20,20,54,55,12,43,54,15,81,26,15,65,34,37,50,20,29,70,68,14,52,46,14,79,43,18,60,70

%N Number of primes of the form k^2 + k + 2n - 1 for k = 0..2n-1.

%H Seiichi Manyama, <a href="/A188424/b188424.txt">Table of n, a(n) for n = 1..5000</a>

%e a(21) = 40 because the polynomial k^2 + k + 41 generates 40 distinct primes for k = 0, 1, .., 39.

%p with(numtheory):for n from 1 by 2 to 200 do:m:=0:for k from 0 to n do: x:=k^2+k+n:if

%p   type(x,prime)=true then m:=m+1:else fi:od:printf(`%d, `,m):od:

%Y Cf. A005846, A056561.

%K nonn

%O 1,2

%A _Michel Lagneau_, Mar 30 2011