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 A305629 Number of values of k, 0 < k < n, for which (2*n^2 + 2*k*n - k^2 - k)/2 is prime. 0
 0, 0, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 0, 3, 3, 1, 3, 5, 2, 2, 4, 2, 1, 4, 3, 2, 4, 1, 4, 4, 2, 4, 4, 3, 1, 3, 2, 4, 12, 3, 2, 7, 1, 7, 15, 3, 4, 6, 3, 8, 8, 2, 4, 10, 6, 7, 7, 3, 6, 16, 3, 4, 6, 3, 8, 7, 4, 5, 11, 5, 4, 7, 5, 8, 12, 2, 12, 8, 4, 16, 9, 3, 8, 24, 6, 8, 11, 5, 8, 19, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,9 COMMENTS It appears that a(A046174(n)) = 0. LINKS PROG (PARI) a(n) = sum(k=1, n-1, isprime((2*n^2+2*k*n-k^2-k)/2)) CROSSREFS Cf. A046174. Sequence in context: A181089 A341894 A171932 * A214664 A214666 A320471 Adjacent sequences:  A305626 A305627 A305628 * A305630 A305631 A305632 KEYWORD nonn AUTHOR Gionata Neri, Jul 08 2018 STATUS approved

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Last modified May 14 22:10 EDT 2021. Contains 343903 sequences. (Running on oeis4.)