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Values of n for which A000224(n)=Ceiling[(n+1)/4], where A000224(n) is the number of squares mod n.
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%I #3 Mar 30 2012 17:37:54

%S 1,4,8,12,20,28,44,45,52,63,68,76,92,116,124,126,148,164,172,175,188,

%T 212,236,244,268,284,292,316,332,350,356,388,404,412,428,436,452,508,

%U 524,548,556,596,604,628,652,668,692,716,724,764,772,788,796,844,892

%N Values of n for which A000224(n)=Ceiling[(n+1)/4], where A000224(n) is the number of squares mod n.

%C Conjecture. If n>4 and a(n) is a multiple of 4, then a(n)/4 is a prime. (This has been verified up to n = 2000.)

%Y Cf. A000224, A123722.

%K nonn

%O 1,2

%A _John W. Layman_, Oct 12 2006