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%I #6 Dec 05 2013 19:56:21
%S 1,3,6,15,21,36,78,1770,2628,330078,1160526,1106921826,27467109390,
%T 3405462502501956,464491597897585896,35168538277628662422146736,
%U 113107978211040574688911417114776,158163225773885113469535108323447683287341095656
%N For n > 2, a(n) is the smallest triangular number > a(n-1) and congruent to a(n-1) (mod a(n-2)).
%e a(7) == a(6) (mod a(5)), -> 78 -36 = 42 = 2*21.
%Y Cf. A087360.
%K nonn
%O 1,2
%A _Amarnath Murthy_, Sep 08 2003
%E More terms from _David Wasserman_, May 19 2005