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A145046 2*A002330(n+1)*A002331(n+1). 14

%I

%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 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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Last modified September 23 15:54 EDT 2017. Contains 292361 sequences.