A097159 - OEIS

%I #6 Mar 30 2012 17:31:05

%S 2,7,11,19,43,67,83,131,283,277,467,479,1907,1607,2543,1559,5443,5711,

%T 6389,14969,25703,10559,20747,52057,136223,90313,162263,18191,167107,

%U 31391,376589,607153,671947

%N Smallest prime p such that there are n consecutive quadratic residues mod p.

%C Additional terms less than 10^6: a(35)=298483, a(36)=422231, a(40)=701399 and a(42)=366791. - _T. D. Noe_, Apr 03 2007

%e a(22)=10559, a(23)=20747 & a(28)=18191.

%t f[l_, a_] := Module[{A = Split[l], B}, B = Last[ Sort[ Cases[A, x : {a ..} :> { Length[x], Position[A, x][[1, 1]] }] ]]; {First[B], Length[ Flatten[ Take[A, Last[B] - 1]]] + 1}]; g[n_] := g[n] = f[ JacobiSymbol[ Range[ Prime[n] - 1], Prime[n]], 1][[1]]; g[1] = 1; a = Table[0, {30}]; Do[b = g[n]; If[ a[[b]] < 31 && a[[b]] == 0, a[[b]] = n; Print[b, " = ", Prime[n]]], {n, 2555}]

%Y Cf. A002307, A097160, A097161.

%Y Cf. A129201.

%K nonn

%O 1,1

%A _Robert G. Wilson v_, Jul 28 2004

%E More terms from _T. D. Noe_, Apr 03 2007