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 A133254 #11 Sep 23 2024 06:29:06
%S A133254 2,4,5,7,10,11,12,14,15,16,17,19,22,24,25,26,28,29,30,31,32,35,37,39,
%T A133254 40,42,44,45,46,49,50,51,52,53,54,55,56,57,59,61,64,65,67,70,71,72,74,
%U A133254 75,77,79,80,81,82,84,85,87,91,92,94,95,96,100,101,102,103
%N A133254 Sums of a triangular number A000217 > 0 and a square A000290 > 0.
%F A133254 {a + b such that a is in A000217 and b is in A000290 and a,b > 0}. Sum set of {n^2: n>0} and {n*(n+1)/2: n>0}.
%e A133254 a(1) = 2 = 1 + 1 = A000217(1) + A000290(1).
%e A133254 a(2) = 4 = 1 + 3 = A000217(2) + A000290(1).
%e A133254 a(3) = 5 = 1 + 4 = A000217(1) + A000290(2).
%e A133254 a(4) = 7 = 3 + 4 = A000217(2) + A000290(2) = 6 + 1 = A000217(2) + A000290(1).
%e A133254 a(5) = 10 = 1 + 9 = A000217(1) + A000290(3) = 6 + 4 = A000217(3) + A000290(2).
%t A133254 With[{nn=70},Take[Union[Flatten[Outer[Plus,Accumulate[Range[nn]],Range[nn]^2]]],nn]] (* _Harvey P. Dale_, Feb 27 2013 *)
%Y A133254 Cf. A000217, A000290.
%K A133254 easy,nonn
%O A133254 1,1
%A A133254 _Jonathan Vos Post_, Dec 19 2007
%E A133254 Corrected by _Harvey P. Dale_, Feb 27 2013