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 A188424 Number of primes of the form k^2 + k + 2n - 1 for k = 0..2n-1. 4
 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, 9, 34, 21, 5, 19, 36, 13, 28, 18, 7, 31, 18, 19, 34, 15, 14, 27, 27, 11, 41, 31, 11, 68, 16, 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Seiichi Manyama, Table of n, a(n) for n = 1..5000 EXAMPLE a(21) = 40 because the polynomial k^2 + k + 41 generates 40 distinct primes for k = 0, 1, .., 39. MAPLE 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 type(x, prime)=true then m:=m+1:else fi:od:printf(`%d, `, m):od: CROSSREFS Cf. A005846, A056561. Sequence in context: A011172 A193028 A203631 * A220588 A346262 A185356 Adjacent sequences: A188421 A188422 A188423 * A188425 A188426 A188427 KEYWORD nonn AUTHOR Michel Lagneau, Mar 30 2011 STATUS approved

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Last modified March 30 14:20 EDT 2023. Contains 361622 sequences. (Running on oeis4.)