%I A055264
%S A055264 0,1,3,6,9,10,12,15,18,19,21,24,27,28,30,33,36,37,39,42,45,46,48,51,54,
%T A055264 55,57,60,63,64,66,69,72,73,75,78,81,82,84,87,90,91,93,96,99,100,102,
%U A055264 105,108,109,111,114,117,118,120,123,126,127,129,132,135,136,138,141
%N A055264 Possible values of A055263; numbers equal to 0, 1, 3 or 6 modulo 9.
%C A055264 The terms are the possible digit sums of a triangular number. - Amarnath 
               Murthy (amarnath_murthy(AT)yahoo.com), Jan 09 2002
%F A055264 a(n) =a(n-4)+9 =9*floor[n/4]+[n mod 4]*(1+[n mod 4])/2
%F A055264 G.f.: x(1+2x+3x^2+3x^3)/((1-x)^2(1+x)(1+x^2)). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 
               Sep 30 2008]
%Y A055264 Cf. A055263.
%Y A055264 Sequence in context: A022304 A055632 A133006 this_sequence A113502 A061904 
               A111359
%Y A055264 Adjacent sequences: A055261 A055262 A055263 this_sequence A055265 A055266 
               A055267
%K A055264 easy,nonn
%O A055264 0,3
%A A055264 Henry Bottomley (se16(AT)btinternet.com), May 08 2000