A231819 Least positive k such that k*n^2 - 1 is a prime, or 0 if no such k exists.

3, 1, 2, 2, 6, 2, 2, 2, 8, 2, 2, 3, 2, 3, 2, 5, 2, 2, 8, 5, 2, 2, 8, 2, 2, 3, 6, 2, 12, 3, 8, 5, 10, 2, 6, 2, 12, 2, 2, 3, 2, 2, 2, 3, 2, 2, 18, 3, 2, 2, 8, 2, 20, 3, 6, 2, 18, 3, 2, 3, 12, 2, 2, 2, 6, 7, 8, 6, 2, 3, 14, 3, 2, 3, 6, 2, 6, 3, 8, 2, 2, 5, 6, 5, 2

Offset

1,1

Links

Table of n, a(n) for n=1..85.

Mathematica

Table[k = 1; While[! PrimeQ[k*n^2 - 1], k++]; k, {n, 100}] (* T. D. Noe, Nov 18 2013 *)

Crossrefs

Cf. A035092 (least k such that k*(n^2)+1 is a prime).

Cf. A175763 (least k such that k*(n^n)+1 is a prime).

Cf. A035093 (least k such that k*n!+1 is a prime).

Cf. A193807 (least k such that n*(k^2)+1 is a prime).

Cf. A231119 (least k such that n*(k^k)+1 is a prime).

Cf. A057217 (least k such that n*k!+1 is a prime).

Cf. A034693 (least k such that n*k +1 is a prime).

Cf. A231818 (least k such that k*(n^n)-1 is a prime).

Cf. A083663 (least k such that k*n!-1 is a prime).

Cf. A231734 (least k such that n*(k^2)-1 is a prime).

Cf. A231735 (least k such that n*(k^k)-1 is a prime).

Cf. A231820 (least k such that n*k!-1 is a prime).

Cf. A053989 (least k such that n*k -1 is a prime).

Sequence in context: A117494 A342913 A221490 * A286546 A201282 A234522

Adjacent sequences: A231816 A231817 A231818 * A231820 A231821 A231822

Keyword

nonn

Author

Alex Ratushnyak, Nov 13 2013

Status

approved