%I #10 Mar 23 2023 03:45:11

%S 1,1,10,5,35,14,21,30,165,55,286,91,455,35,170,51,969,285,1330,385,

%T 1771,506,23,26,13,91,406,1015,4495,310,341,374,6545,1785,7770,2109,

%U 9139,2470,2665,2870,12341,3311,14190,3795,16215,1081,94,1,17,221,23426,689,2915,770,7315,7714,32509,8555

%N Squarefree part of the n-th tetrahedral number.

%F a(n) = A007913(A000292(n)).

%o (Python)

%o from sympy.ntheory.factor_ import core

%o def A361671(n): return core(n*(n*(n + 3) + 2)//6) # _Chai Wah Wu_, Mar 20 2023

%o (PARI) a(n) = core(n*(n+1)*(n+2)/6); \\ _Michel Marcus_, Mar 22 2023

%Y Cf. A007913, A000292, A361670 (of triangular), A083481 (of oblong).

%Y Cf. A003556 (squarefree part is 1).

%K nonn,easy

%O 1,3

%A _R. J. Mathar_, Mar 20 2023