%I #10 Nov 23 2020 08:25:38
%S 1,1,0,0,1,2,0,1,2,0,1,4,6,1,4,6,1,6,12,1,6,18,25,8,24,25,8,30,49,10,
%T 42,73,10,48,121,132,60,145,132,72,217,254,84,265,374,96,361,616,114,
%U 433,856,846,553,1218,864,649,1578,1602,817,2180,2340,937,2780,3798,1129,3622
%N Number of compositions (ordered partitions) of n into distinct parts congruent to 1 mod 3.
%H <a href="/index/Com#comp">Index entries for sequences related to compositions</a>
%F G.f.: Sum_{k>=0} k! * x^(k*(3*k - 1)/2) / Product_{j=1..k} (1 - x^(3*j)).
%e a(12) = 6 because we have [7, 4, 1], [7, 1, 4], [4, 7, 1], [4, 1, 7], [1, 7, 4] and [1, 4, 7].
%t nmax = 65; CoefficientList[Series[Sum[k! x^(k (3 k - 1)/2)/Product[1 - x^(3 j), {j, 1, k}], {k, 0, nmax}], {x, 0, nmax}], x]
%Y Cf. A000930, A016777, A032020, A032021, A035382, A261612, A337548, A339059, A339060.
%K nonn
%O 0,6
%A _Ilya Gutkovskiy_, Nov 22 2020