This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A102857 #14 Jun 05 2025 07:52:41
%S A102857 0,1,4,5,10,11,14,15,20,21,24,25,30,31,34,35,36,39,40,45,46,49,55,56,
%T A102857 57,59,60,61,65,66,67,70,76,77,80,84,85,86,88,89,91,92,94,95,98,101,
%U A102857 104,105,108,111,114,119,120,121,123,124,125,129,130,131,134,139
%N A102857 Sum of 1, 2 or 3 distinct tetrahedral numbers.
%H A102857 R. J. Mathar, <a href="/A102857/b102857.txt">Table of n, a(n) for n = 1..4545</a>
%t A102857 Module[{nn=10,tetra},tetra=Table[(n(n+1)(n+2))/6,{n,nn}];Rest[Union[ Total/@ Subsets[tetra,3]]]] (* _Harvey P. Dale_, Nov 17 2017 *)
%Y A102857 Cf. A104246, A102795-A102801, A102803-A102806, A102855, A102857, A102858.
%Y A102857 Cf. A102856 (subsequence), A102802 (subsequence 3 dist. posit.).
%K A102857 nonn
%O A102857 1,3
%A A102857 _Jud McCranie_, Mar 01 2005
%E A102857 a(1)=0 prepended. - _R. J. Mathar_, Jun 05 2025