Search: id:A106545
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%I A106545
%S A106545 0,4,9,16,25,36,49,64,81,100,0,144,169,196,225,256,0,324,361,400,441,
%T A106545 484,0,576,0,676,729,784,841,900,0,1024,1089,1156,1225,1296,1369,1444,
               0,
%U A106545 1600,0,1764,1849,1936,0,2116,2209,2304,2401,2500,0,2704,0,2916,3025
%N A106545 a(n) = n^2 if n^2 is the sum of two primes, otherwise a(n) = 0.
%C A106545 For odd n, n^2 is odd so the two primes must be opposite in parity. Lesser 
               prime must be 2 and greater prime must be n^2-2. Thus for odd n, 
               n^2 is the sum of two primes iff n^2-2 is prime.
%F A106545 a(n) = n^2 - A106544(n).
%e A106545 a(2) = 2^2 = 4 = 2+2, a(5) = 5^2 = 25 = 23+2 (two primes).
%e A106545 a(1) = 0 because the sum of two primes is at least 4 and a(11) = 0 because 
               11^2 - 2 = 119 = 7*17 is composite.
%Y A106545 Cf. A106544-A106548, A106562-A106564, A106571, A106573-A106575, A106577.
%Y A106545 Sequence in context: A048387 A035121 A080151 this_sequence A093837 A069821 
               A000290
%Y A106545 Adjacent sequences: A106542 A106543 A106544 this_sequence A106546 A106547 
               A106548
%K A106545 easy,nonn
%O A106545 1,2
%A A106545 Alexandre Wajnberg (alexandre.wajnberg(AT)ulb.ac.be), May 08 2005
%E A106545 Edited and extended by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de) 
               and Ray Chandler (rayjchandler(AT)sbcglobal.net), May 12 2005

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