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Number of primes of form 4k+3 between n^2 and (n+1)^2.
6

%I #13 Oct 06 2021 21:24:15

%S 1,1,1,2,1,2,1,3,1,2,3,3,2,3,3,3,2,3,3,3,4,5,3,4,4,4,3,5,4,4,5,5,4,4,

%T 5,5,4,8,8,5,4,6,5,6,7,5,5,7,5,7,7,7,6,8,4,5,11,5,9,8,6,11,7,7,7,7,8,

%U 10,5,12,10,5,9,10,7,13,8,8,11,5,10,9,13,9,6,9,12,7,7,11,10,9,12,11,10,10

%N Number of primes of form 4k+3 between n^2 and (n+1)^2.

%C Related to Legendre's conjecture that there is always a prime between two consecutive squares.

%H Seiichi Manyama, <a href="/A077767/b077767.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from T. D. Noe)

%e a(8)=3 because primes 67, 71 and 79 are between squares 64 and 81

%t maxN=100; a=Table[0, {maxN}]; maxP=PrimePi[(maxN+1)^2]; For[i=1, i<=maxP, i++, p=Prime[i]; If[Mod[p, 4]==3, j=Floor[Sqrt[p]]; a[[j]]++ ]]; a

%t p3[{a_,b_}]:=Module[{p=Prime[Range[PrimePi[a]+1,PrimePi[b]]]},Count[p,_?(Mod[#,4]==3&)]]; p3/@Partition[Range[100]^2,2,1] (* _Harvey P. Dale_, Feb 20 2020 *)

%Y Cf. A002145, A014085, A077766.

%K nonn

%O 1,4

%A _T. D. Noe_, Nov 20 2002