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Numbers m, such that there is no solution m = x + y + 3*z, with triangular numbers x, y, z.
3

%I #7 Jul 21 2013 13:18:53

%S 8,17,26,35,44,53,62,71,77,80,89,98,107,116,125,134,143,152,158,161,

%T 170,179,188,197,206,215,224,233,239,242,251,260,269,278,287,296,305,

%U 314,320,323,332,341,350,359,368,377,386,395,401,404,413,422,431,440

%N Numbers m, such that there is no solution m = x + y + 3*z, with triangular numbers x, y, z.

%C A224823(a(n)) = 0;

%C terms not of the form 9*k+8: 77,158,239,320,401,482,563,644,698,... .

%H Reinhard Zumkeller, <a href="/A224829/b224829.txt">Table of n, a(n) for n = 1..1000</a>

%o (Haskell)

%o a224829 n = a224829_list !! n

%o a224829_list = filter ((== 0) . a224823) [0..]

%Y Cf. A017257 (subsequence), A000217.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Jul 21 2013