# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a094048 Showing 1-1 of 1 %I A094048 #14 Oct 19 2017 03:14:29 %S A094048 2,18,4,70,6,32,182,29718,1068,500,5604,10,8890182,776,1744,113582, %T A094048 4832118,1118,1111225770,1764132,14,1710,23156,71011068,16,82, %U A094048 8920484118,1063532,2482,126862368,352618 %N A094048 Let p(n) be the n-th prime congruent to 1 mod 4. Then a(n) = the least m for which m^2+1=p(n)*k^2 has a solution. %C A094048 Subsequence of A191860. [_Reinhard Zumkeller_, Jun 18 2011] %t A094048 f[n_] := Block[{y = 1}, While[ !IntegerQ[ Sqrt[n*y^2 - 1]], y++ ]; Sqrt[n*y^2 - 1]]; lst = {}; Do[p = Prime@ n; If[ Mod[p, 4] == 1, AppendTo[lst, f@p]; Print[{n, Prime@n, f@p}]], {n, 66}]; lst %o A094048 (Haskell) %o A094048 a094048 n = head [m | m <- map (a037213 . subtract 1 . (* a002144 n)) %o A094048 (tail a000290_list), m > 0] %o A094048 -- _Reinhard Zumkeller_, Jun 13 2015 %Y A094048 Cf. A002144, A094049 (associated k), A130226, A137351, A179073. %Y A094048 Cf. A000196, A037213, A000290. %K A094048 nonn %O A094048 1,1 %A A094048 _Matthijs Coster_, Apr 29 2004 %E A094048 Edited by _Don Reble_, Apr 30 2004 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE