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%I #4 Oct 02 2021 16:51:24
%S 4,12,8,20,12,40,28,60,48,80,72,20,60,112,88,140,132,52,180,168,28,60,
%T 208,120,32,260,252,160,68,312,308,288,180,272,252,340,228,40,120,420,
%U 408,280,168,380,220,440,420,532,520,48,368,240,612,608,200,572,300,552,52,260
%N a(n) = 2*A002330(n+1) * A002331(n+1).
%e The following table shows the relationship
%e between several closely related sequences:
%e Here p = A002144 = primes == 1 mod 4, p = a^2+b^2 with a < b;
%e a = A002331, b = A002330, t_1 = ab/2 = A070151;
%e p^2 = c^2+d^2 with c < d; c = A002366, d = A002365,
%e t_2 = 2ab = A145046, t_3 = b^2-a^2 = A070079,
%e with {c,d} = {t_2, t_3}, t_4 = cd/2 = ab(b^2-a^2).
%e ---------------------------------
%e .p..a..b..t_1..c...d.t_2.t_3..t_4
%e ---------------------------------
%e .5..1..2...1...3...4...4...3....6
%e 13..2..3...3...5..12..12...5...30
%e 17..1..4...2...8..15...8..15...60
%e 29..2..5...5..20..21..20..21..210
%e 37..1..6...3..12..35..12..35..210
%e 41..4..5..10...9..40..40...9..180
%e 53..2..7...7..28..45..28..45..630
%e .................................
%Y 4 times A070151, or (apart from initial term) twice A145019.
%Y Cf. A070079.
%K nonn
%O 0,1
%A _N. J. A. Sloane_, Feb 25 2009
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