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 A171970 #15 Feb 16 2025 08:33:11 %S A171970 0,1,2,3,4,5,6,6,7,8,9,10,11,12,12,13,14,15,16,17,18,19,19,20,21,22, %T A171970 23,24,25,25,26,27,28,29,30,31,32,32,33,34,35,36,37,38,38,39,40,41,42, %U A171970 43,44,45,45,46,47,48,49,50,51,51,52,53,54,55,56,57,58,58,59,60,61,62,63 %N A171970 Integer part of the height of an equilateral triangle with side length n. %H A171970 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/EquilateralTriangle.html">Equilateral Triangle</a> %H A171970 Wikipedia, <a href="http://en.wikipedia.org/wiki/Equilateral_triangle">Equilateral triangle</a> %F A171970 a(n) = floor(n*sqrt(3)/2). %F A171970 a(n) = floor(A022838(n)/2). %F A171970 a(n)*A004526(n) <= A171971(n) %F A171970 a(n)*A005843(n) <= A171972(n). %o A171970 (PARI) a(n)=sqrtint(3*n^2\4) \\ _Charles R Greathouse IV_, Jan 06 2013 %Y A171970 Beatty sequence of A010527. %Y A171970 Cf. A022838, A004526, A005843, A171971, A171972. %K A171970 nonn,easy %O A171970 1,3 %A A171970 _Reinhard Zumkeller_, Jan 20 2010