%I A056527
%S A056527 2,4,5,7,11,13,14,16,20,22,23,25,29,31,32,34,38,40,41,43,47,49,50,52,
%T A056527 56,58,59,61,65,67,68,70,74,76,77,79,83,85,86,88,92,94,95,97,101,103,
%U A056527 104,106,110,112,113,115,119,121,122,124,128,130,131,133,137,139,140
%N A056527 Numbers where iterated sum of digits of square settles down to a cyclic 
               pattern (in fact 13, 16, 13, 16, ...).
%C A056527 Numbers == 2, 4, 5 or 7 mod 9, i.e. such that n^4 is not congruent to 
               n^2 mod 9
%C A056527 Numbers congruent to {2, 4, 5, 7} mod 9.
%e A056527 a(1)=2 because iteration starts 2, 4, 7, 13, 16, 13, 16, ....
%Y A056527 Cf. A004159 for sum of digits of square, A056020 where iteration settles 
               to 1, A056020 where iteration settles to 9, also A056528, A056529. 
               Unhappy numbers A031177 deal with iteration of square of sum of digits 
               not settling to a single result.
%Y A056527 Sequence in context: A099522 A108464 A128815 this_sequence A147991 A033160 
               A110924
%Y A056527 Adjacent sequences: A056524 A056525 A056526 this_sequence A056528 A056529 
               A056530
%K A056527 base,easy,nonn
%O A056527 1,1
%A A056527 Henry Bottomley (se16(AT)btinternet.com), Jun 19 2000