Search: id:A054799
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%I A054799
%S A054799 3,5,11,17,29,41,59,71,101,107,137,149,179,191,197,227,239,269,281,311,
%T A054799 347,419,431,434,461,521,569,599,617,641,659,809,821,827,857,881,1019,
%U A054799 1031,1049,1061,1091,1151,1229,1277,1289,1301,1319,1427,1451,1481,1487
%N A054799 Integers n such that Sigma[n+2]=Sigma[n]+2, Sigma=A000203, sum of divisors 
               of n.
%C A054799 Below 1000000 only 3 composite numbers were found: 434, 8575, 8825. This 
               sequence is different from A001359.
%D A054799 Sivaramakrishnan, R. (1989): Classical Theory of Arithmetical Functions., 
               M.Dekker Inc., New York, Problem 12 in Chapter V., p. 81.
%e A054799 n = 434, divisors = {1, 2, 7, 14, 31, 62, 217, 434}, Sigma[434] = 768, 
               Sigma[436] = 770; n = 8575, divisors = {1, 5, 7, 25, 35, 49, 175, 
               245, 343, 1225, 1715, 8575}, Sigma[8575] = 12400, Sigma[8577] = 12402; 
               n = 8825, divisors = {1, 5, 25, 353, 1765, 8825}, Sigma[8525] = 10974, 
               Sigma[8527] = 10976
%Y A054799 Cf. A000203, A001359, A050507.
%Y A054799 Sequence in context: A069233 A063700 A078859 this_sequence A001359 A096292 
               A078864
%Y A054799 Adjacent sequences: A054796 A054797 A054798 this_sequence A054800 A054801 
               A054802
%K A054799 nonn
%O A054799 1,1
%A A054799 Labos E. (labos(AT)ana.sote.hu), May 22 2000

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