A094049 - OEIS

A094049

Let p(n) be the n-th prime congruent to 1 mod 4. Then a(n) = the least k for which m^2+1=p(n)*k^2 has a solution.

1, 5, 1, 13, 1, 5, 25, 3805, 125, 53, 569, 1, 851525, 73, 149, 9305, 385645, 85, 82596761, 126985, 1, 113, 1517, 4574225, 1, 5, 535979945, 63445, 145, 7170685, 19805, 55335641, 493, 3793, 265, 65, 1027776565, 1

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..38.

MATHEMATICA

f[n_] := Block[{y = 1}, While[ !IntegerQ[ Sqrt[n*y^2 - 1]], y++]; y]; lst = {}; Do[p = Prime@n; If[Mod[p, 4] == 1, AppendTo[lst, f@p]; Print[{n, f@p}]], {n, 66}]; lst

CROSSREFS

Cf. A002144, A094048.

Sequence in context: A327797 A062264 A276738 * A286254 A322664 A286457

Adjacent sequences: A094046 A094047 A094048 * A094050 A094051 A094052

KEYWORD

nonn

AUTHOR

Matthijs Coster, Apr 29 2004

EXTENSIONS

Edited by Don Reble, Apr 30 2004

STATUS

approved