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 A003556 #31 Mar 01 2019 01:53:53 %S A003556 0,1,4,19600 %N A003556 Numbers that are both square and tetrahedral. %C A003556 A. J. J. Meyl proved in 1878 that only 1, 4 and 19600 are both square and tetrahedral. See link. [_Bernard Schott_, Dec 23 2012] %D A003556 D. Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, 600. %D A003556 D. Wells, The Penguin Dictionary of Curious and Interesting Numbers, p. 165 (Rev. ed. 1997). %H A003556 M. Gardner, <a href="/A001110/a001110.jpg">Letter to N. J. A. Sloane, circa Aug 11 1980</a>, concerning A001110, A027568, A039596, etc. %H A003556 A. J. J. Meyl, <a href="http://archive.numdam.org/item/NAM_1878_2_17__464_1/">Question 1194</a>, Nouvelles Annales de Mathématiques, 2ème série, tome 17 (1878), p. 464-467. %e A003556 From _Bernard Schott_, Dec 23 2012: (Start) %e A003556 If S(n) = n^2 and T(m) = m*(m+1)*(m+2)/6, then %e A003556 -> S(1)= T(1) = 1; %e A003556 -> S(2)= T(2) = 4; %e A003556 -> S(140) = T(48) = 19600. (End) %t A003556 Select[Rest[FoldList[Plus, 0, Rest[FoldList[Plus, 0, Range[50000]]]]], IntegerQ[Sqrt[ # ]]&] %t A003556 Intersection[Binomial[# + 2, 3]&/@Range[0, 10000], Range[0,409000]^2] (* _Harvey P. Dale_, Feb 01 2011 *) %Y A003556 Intersection of A000290 and A000292. %K A003556 nonn,fini,full %O A003556 1,3 %A A003556 _N. J. A. Sloane_